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Sink or Float Experiment for Preschoolers

Last updated on October 28, 2019

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Set up a sink or float experiment  to teach toddlers and preschoolers about density and buoyancy. This play-based learning activity combines a science activity  and a water activity, and for some extra fun, we’re adding a colourful twist. 

My kids love science. Thankfully, there are tons of easy science activities that we can do at home to quench their thirst for scientific discovery. A simple sink or float activity is a great beginner science experiment that will introduce your toddlers and preschoolers to density and buoyancy .

Physics for Preschoolers

This sink or float experiment is a simple physics experiment that will encourage your child to make predictions and observations about buoyancy and density. Through their observations, they’ll learn that buoyant objects float and dense objects sink, and if they want to be true little scientists, they can even record their predictions.

Low-prep activity for indoors or out

We love to do this low-prep activity in the backyard when the weather is nice. I set up this particular sink or float experiment three days ago and the kids have set it up themselves every day since. We’ve been enjoying it on the patio so they can get as wet and wild as they like with it.

Indoors, kids can do this activity at the kitchen sink, in the bathtub or on the floor with a tub or basin filled with water.

Engage their senses with a colourful twist!

We love adding a packet of   jello powder or juice crystals to the water. Not only does this colour the water, it gives it a wonderfully fruity scent.

The kids get a thrill out of watching the water change colour, and the pop of colour and the scent have educational benefits as well : kids retain more information when more than one sense is engaged.

What you’ll need for a sink or float activity

• waterproof toys and household items (see suggested items below)
• a container to do the experiment in i.e. plastic tub, basin, pot, bucket etc.
• drinking straws (optional)
• Jello or juice crystals (optional)

Note:  If you’re doing this experiment indoors, place a plastic table cloth or some beach towels under the bin to soak up any spills.

Suggested items for a sink or float experiment:

Items that sink.

• metal utensils
• toy car/truck
• glass gemstones or marbles (not suitable for toddlers)

items that float

• stick or popsicle stick
• bathtub toys
• foam shapes
• rubber ball

How to do an educational sink or float experiment

Start off by collecting the items for your experiment. If you give your kids a list of things to collect, this  part of the activity can be a fun little scavenger hunt for your kids.

Fill a tub or bucket with lukewarm water.

If colouring your water, you can add it now or once the toys have been added.

Before adding your objects to the water, ask your children to predict which objects they think will sink and which will float.

In a classroom, this can be done by a show of hands in favour of an item sinking or floating. If you’re doing this activity with a large group, it can be fun to have a tally beside each item to indicate each child’s hypothesis.

Now, have the kids drop the objects, one by one, into the water one observe what happens.

Once all of the items are in the water, you can extend the activity by giving the kids drinking straws to blow the floating items around. This is a fun way to teach children about kinetic energy as the air they blow through the straw propels the floating items forward.

The science behind the sink or float experiment

Before explaining why items sink or float, ask your children why they think an object sinks or floats. They may guess it’s because of size or weight or construction.

Then, explain that items sink or float based on their density . Density is determined by how close or far apart molecules are within an item. Molecules are tiny and only visible by a microscope. You can refer to this article to help explain this  to your kids. I’ve also listed a few books below that you can read with your kids before doing the experiment.

You can also use this opportunity to explain why blowing through a straw moves the floating items around the bin (kinetic energy).

Once you have prompted their learning by explaining the science behind the activity, allow your children to replicate the experiment as many times as they please. This will help to solidify their knowledge and reap the benefits of play-based learning.

Since first doing our sink or float experiment, my kids have set up their own version of the activity every day since. It’s been amazing to see their fascination with such an educational activity.

More easy science activities:

Three Chemical Reactions for Kids

Water Displacement Experiment for Preschoolers

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Reader Interactions

Lindsay Robinson

April 14, 2020 at 11:22 pm

Hi, I really enjoyed reading about your lesson. Thank you for the ideas. Where did you get the clear plastic buckets?

Jackie Currie

April 16, 2020 at 8:59 am

I’m not sure where that bucket came from, but if you search for “clear ice buckets” on Amazon, there are quite a few options there, Lindsay.

December 10, 2021 at 3:50 pm

What if, before explaining why things sink or float, you help them figure out ways to test their hypothesis? For example, if they guessed size, can they figure out what size is the cutoff? Can they find any objects that sink at a size they predict would float, or vice versa? Same with weight or whatever other theory they come up with.

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Play to Learn Preschool

A delightful preschool experience

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Sink or Float Experiment

This sink or float experiment is a preschooler’s dream! Students remain engaged in an inquiry-based learning project, full of surprises and sensory experiences that they will talk about all year long.

Predicting Outcomes in Preschool

Predicting is an exciting skill that comes with practice. In preschool, students predict what will come next in class based on the routines established throughout the year. They may also predict if their baseball team will win an upcoming game based on how they’ve played in the past. Recognizing what has previously happened to predict what might happen is a skill that can be put to the test in the preschool classroom in a number of ways.

• What will happen next in the story? (Predictable patterns are HUGE in preschool books !)
• What do you get when you mix red with yellow ?
• Do you think sandpaper is rough or smooth? Which of your 5 senses helped you make that prediction?

Does It Sink? Does It Float?

This sink or float experiment is perfect for the beginning of the preschool year because it teaches important, familiar vocabulary (many students know the word float from swimming) and requires very minimal preparation. Begin by talking about the terminology ( sink and float ). Show a variety of objects and allow students to hold each one. Discuss predictions for each item. Why do you think it will float? (“It’s very light.”) Why do you think it will sink?

Ideas Items to Test:

• Pencils & crayons
• Spoons (both plastic and metal)
• Lemons & Limes (Check out this cool article about these!)

Ask the students to make predictions and post them on a pocket chart tally marks or name cards. For each item, count the number of students who think it will sink versus the number that thinks it will float. This is an excellent time for a bit of math review using words like more or less .

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Let the Fun Begin!

Once predictions have been made, it is time for the fun to really start! If possible, take the experiment outside or protect an indoor area with a plastic table cloth as it will inevitably be a little wet. There is only a little setup and a few supplies needed to make this experiment one the students will not soon forget.

Supplies Needed for the Sink or Float Experiment:

• a bucket or tub of water
• items to test in the experiment

As a starting point, begin by allowing students to explore apples in the water. Exploration is a critical step in developing an understanding of a concept. Students may try and push the apple to the bottom, only to watch it float back up to the top.

Does the apple float or sink?

Once students have explored the apples, come back and discuss what they discovered as a class. Were their predictions correct? Remind students that predictions are guesses, and it is okay if they guessed wrong – that’s how we learn! Some students may even begin to make connections such as “I knew it would float. I went bobbing for apples last year.”

More Sink or Float Experiment Fun

Once students have had a chance to explore the buoyancy of the apple, the next step is to extend the learning. Challenge the students to go back inside the classroom and find something else that would float. Discuss why they think it would float. Is it similar to the apple in any way? These discussions are great ways to build connections.

Next, ask students to find things that will sink. This can be a bit more challenging. Many of the heavy things in the classroom (blocks, for example) that the students think would sink are made of wood, which floats. Guide students as necessary, then allow them to continue to search for similar items as needed.

Other Preschool Science Experiments

Sometimes, teachers are intimidated by planning science lessons because it sounds like a big and complicated project. Preschool science does not have to be that way, though! Just exploring the world around them is enough to spark a curiosity that will build knowledge for years to come.

Check out this Resource from my Shop!

Preschool Science Centers for the Year

Students will enjoy hands-on  SCIENCE CENTERS  all year long. Each unit includes a list of supplies for each topic, learning objectives, lesson ideas, as well as photos and activities that students will want to explore again and again! Encourage young learners to ask questions, make observations, and develop scientific thinking skills.

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Easy Sink or Float Experiment For Kids

Open the fridge and pantry drawers for this sink or float experiment. You have everything you need to test whether objects sink or float in the water with common household items. Plus, grab the free printable worksheets to add to extend the activity.

Sink or Float Experiment

We used items from the kitchen for our sink and float experiment. Plus, I am sure your child will be able to come with other fun things to test! You can even have them test a collection of their favorite items, too!

Watch the Video:

💡Read all about the science below! Take a look at more experiments you can do here!

• a large container filled with water
• different fruits and vegetables
• aluminum foil
• aluminum cans
• spoons (both plastic and metal)
• anything your kiddos want to explore
• free printable worksheets (see below)

💡 Tip: You could also try peeling or slicing your vegetables. 

Instructions:

STEP 1. Before you start, have your kiddos predict whether the item will sink or float before placing the object in the water.

STEP 2. Place each object in the water one by one and observe whether it sinks or floats.

If the object floats, it will rest on the water’s surface. If it sinks, it will fall beneath the surface. Read the science info below about why some objects float and some sink.

Extension: Does Aluminum Sink or Float?

The aluminum can, and aluminum foil were some exciting things we tested in our sink or float activity . We noticed the empty can could float, but it would sink when pushed under the water. Also, we could see the air bubbles that helped it float. Have you seen the crushing cans experiment?

Project: Does a full can of soda float, too? Just because something feels heavy doesn’t mean it will sink!

The aluminum foil floats when it is a flat sheet when it is crippled into a loose ball, and even a tight ball. However, if you give it an excellent pound to flatten it, you can make it sink. Removing the air will sink it. Check out this buoyancy activity with tin foil here!

Project: Can you make a marshmallow sink? We tried it with a Peep candy. See it here. What about a paper clip? Check out this experiment here.

Why Do Objects Sink or Float?

Some objects sink, and some objects float, but why is that? The reason is density and buoyancy!

Every state of matter, liquid, solid, and gas, has a different density. All states of matter are made up of molecules, and density is how tightly those molecules are packed together, but it’s not just about weight or size!

Items with molecules packed tighter together will sink, while items made up of molecules that are not as tightly packed together will float. Just because an item is considered a solid doesn’t mean it will sink.

For example, a piece of balsa wood or even a plastic fork. Both are considered “solids,” but both will float. The molecules in either item are not packed together as tightly as a metal fork, which will sink. Give it a try!

If the object is denser than water, it will sink. If it’s less dense, it will float!

Check out more easy density experiments.

Buoyancy is the ability of an object to float or rise in a fluid, such as water or air. It occurs because the upward force exerted by the fluid (liquid or gas) is greater than the downward force of gravity acting on the object.

In simpler terms, buoyancy is how well something floats. Generally, the greater the surface area, the better the buoyancy. You can see this in action with our tin foil boats !

In our sink or float experiment below the vegetables that float are buoyant because the upward force of the water is greater than their weight, helping them stay on the water’s surface. Those that sink are denser than water.

TIP: Discuss how some vegetables might have air pockets inside them, contributing to their buoyancy.

Try This: Do Vegetables Sink or Float?

Generally, fruits and vegetables with higher water content are more likely to float, while those with lower water content or denser structures may sink. Here are some examples:

Fruits and Vegetables That Tend to Float:

These fruits and vegetables have a higher water content and often contain air pockets, making them less dense than water and more likely to float.

Fruits and Vegetables That Tend to Sink:

• Sweet potatoes
• Avocado (when submerged)
• Winter squash

These fruits and vegetables are denser and have less water content, making them more likely to sink in water.

It’s important to note that there can be variations within each type of fruit or vegetable, and factors such as size, ripeness, and the presence of air pockets can influence whether they float or sink. Conducting a simple sink or float experiment with a variety of fruits and vegetables can be a great way to explore these ideas further.

Free Printable Sink or Float Worksheets!

Grab our free sink or float printable worksheets for kids to record their observations! Find more [here] .

More Fun Water Experiments

Check out our list of science experiments for Jr Scientists!

• Walking Water Experiment
• What Materials Absorb Water?
• What Dissolves In Water?
• Saltwater Density Experiment
• Do Oranges Sink or Float?
• Freezing Water

Printable Science Projects For Kids

If you’re looking to grab all of our printable science projects in one convenient place plus exclusive worksheets and bonuses like a STEAM Project pack, our Science Project Pack is what you need! Over 300+ Pages!

• 90+ classic science activities  with journal pages, supply lists, set up and process, and science information.  NEW! Activity-specific observation pages!
• Best science practices posters  and our original science method process folders for extra alternatives!
• Be a Collector activities pack  introduces kids to the world of making collections through the eyes of a scientist. What will they collect first?
• Know the Words Science vocabulary pack  includes flashcards, crosswords, and word searches that illuminate keywords in the experiments!
• My science journal writing prompts  explore what it means to be a scientist!!
• Bonus STEAM Project Pack:  Art meets science with doable projects!
• Bonus Quick Grab Packs for Biology, Earth Science, Chemistry, and Physics

• Pingback: 100+ STEM Projects for Kids (With Free Cheat Sheets)
• Pingback: Scientific Method For Kids

Wonderful idea and great way to kick start our science week in the little room. But the free printable is not there anymore. Is the link broken?

Hi Emily, thank you! It is there towards the bottom of the page. It is possible that your organization is blocking the link. Feel free to email me [email protected]

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B-Inspired Mama

Kids Crafts · Play & Learning Activities · Fun Food · Creative Parenting Tips

Sink or Float Preschool Science Experiment for Fall or Any Season!

By Sarah of Little Bins for Little Hands 10 Comments

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Disclosure:  This blog post, contributed by Sarah of Little Bins for Little Hands , contains affiliate links. As an affiliate and Amazon Associate, I earn from qualifying purchases at no additional cost to you. Please read my  full disclosure policy  for more information.

Sensory play is a wonderful way to learn! Most of the time our sensory bin is filled with dry materials for sensory activities, but we also enjoy using water for sensory play . Although a little messy, water is perfect for indoor sensory play. And, it’s perfect for some easy sink or float preschool learning, too!

Some Easy Fall Sink or Float Preschool Science Fun

It has been a while since we’ve done a sink or float experiment, so I decided to put together a simple fall-themed sink and float activity. My son loves sensor play, so I knew it was time to set up this invitation for water play and scientific discovery.

How to Set Up a Preschool Sink or Float Experiment

It doesn’t get much easier than this preschool science experiment. You simply need a tub of water (or you could even use a sink or bathtub) and two smaller bins or trays .

Then, fill one of the trays with a variety of waterproof objects. You can use any random household objects. Or, choose objects based around a specific theme.

We decided to make ours a Fall sink or float preschool activity. You can do any season, but for an Autumn theme, use objects like…

• mini pumpkins
• mini gourds
• stones or pebbles
• decorative rattan balls
• Fall-themed vase fillers

You can also include some items your child can use as boats, like small baking pans and plastic or styrofoam egg carton pieces . I was hoping to inspire my preschooler to experiment with sinking a floating boat or keeping the boat afloat.

Using the Scientific Method to Hypothesize & Sort Fall Objects

Now, this Fall sink or float experiment is the perfect way to introduce young children to the Scientific Method and inspire some critical thinking. Just invite your child to explore and examine the various objects on the tray while discussing which objects might sink and float. For more advanced scientific learning, discuss the potential effects of size, weight, and density on the objects’ buoyancy.

Then, invite your child to sort the items according to their predictions of buoyancy (whether they think it will sink or float) using the two trays. It’s okay if they sort some items incorrectly; that will make the science experiment more fun.

Preschool Learning with a Fall Sink or Float Experiment

Now, invite your child to test each object in the tub of water to see if the object sinks or floats.

My son was almost in disbelief when some of the items that he thought would sink, like apples, floated. He also predicted that the pebbles would float because they were small, but they sank because they are heavy.

Again, you can discuss the scientific concepts related to their findings (the effects of size, weight, and density on buoyancy). Or, you can simple allow your child to absorb some of these concepts naturally through open-ended play and exploration.

After you have tested each object for buoyancy, invite your child to explore the objects along with the pretend boats (egg crate pieces and baking pans). Challenge them to try to sink the boats by placing objects on them.

My son enjoyed trying different combinations of items in each pan and separating smaller items and bigger items between the different boats. He noticed it took a lot of items to sink the large pan and fewer items to sink the little one. And, it took lighter items and fewer heavier ones. He also observed how just the right amount of items, like gems, in the baking pan would still allow it to float.

Finally, have your child sort the objects again into the trays according to their scientific findings.

For added fun, I showed my son a photo I had taken of the two trays as he had sorted them before the science experiment so he could compare it to his findings. He had fun pointing out the differences. Lots of things he thought would sink actually floated. He remarked how he thought it was cool!

We wrapped up our preschool sink or float experiment with what else? Free play, of course!

Lots of splashing, sinking boats, making waves, and plunking acorns. The floor was a little wet when he finished, but it was all in the name of science!

Full Fall Sink or Float Experiment Instructions:

Easy Fall Sink or Float Preschool Science Experiment

• 1 large sensory bin (or large plastic bin)
• 2 large plastic trays
• silicone muffin pan (optional, ideally Fall-themed)
• plastic food storage containers (optional, various sizes)
• apples (real or artificial)
• mini pumpkins (real or artificial)
• acorns (real or artificial)
• walnuts in shell
• leaves (real or artificial)
• wicker rattan balls
• river rocks
• vase filler (or table scatter, ideally Fall-themed)
• recycled styrofoam egg carton (cut into various sizes)
• Fill sensory bin with around 6 inches of water .

• Demonstrate and discuss the scientific concept of buoyancy by placing one floating and one sinking object in the water inside the sensory bin. Remove them and set aside.

• Encourage imaginative and sensory play during and after the science experiment.

More Preschool Science Supplies and Kits on Amazon:

Get everything you need for the sink and float experiment above right from Amazon…

Or, try some of these all-inclusive preschool science kits and toys that make learning fun and easy….

And, find more educational toys and learning kits for kids in  B-Inspired Mama’s Amazon Shop:  Fun Finds for STEM Learning

Like this Preschool Sink or Float Activity? Save It & Share It!

Don’t forget to save this fun preschool science experiment to come back to. And share it with friends! Simply use the buttons at the top or bottom of this post. Or, click here:  Share on Facebook  |  Tweet It  |  Pin It  |  Email to a Friend

More Ideas for Preschool Sensory Fun:

• 6 Fun Fall Activities from the Kids Co-Op
• Sweet Citrus Sensory Tray
• Animal Maze Play for Fine Motor Development

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Reader Interactions

Alice @ Mums Make Lists says

September 5, 2014 at 8:18 PM

I love this idea Krissy and Sarah. We’re off foraging tomorrow for damsons, crab apples, sloes etc and picking conkers and it will be a fab end of day activity whilst we’re straining the fruit 🙂

Krissy @ B-Inspired Mama says

September 7, 2014 at 9:49 AM

So glad you like it!

September 28, 2013 at 11:55 AM

Sink or float is one of my favorite science experiments. It was always fun to see what they kids predicted and then what other items they wanted to float too. Thank you for linking up this week to the Thoughtful Spot Weekly Blog Hop 🙂

Sugar Aunts says

September 28, 2013 at 3:18 AM

Love this! We’re featuring your post on Share It Saturday this week over at Sugar Aunts! Thanks for linking up 🙂

Allison says

September 27, 2013 at 6:26 PM

Love the fall spin on this activity. I’ll be featuring this on The Sunday Showcase this weekend. Thanks for linking up!

Natalie says

September 27, 2013 at 9:45 AM

I love the items you chose for this experiment. I always find it fascinating that most of items in nature float – probably to spread their seeds… Thanks for sharing with Afterschool!

September 20, 2013 at 7:33 PM

Thank you for sharing! I’ve pinned this 🙂

I found your post through the Friday Flash Blog @ The Jenny Evolution.

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Buggy and Buddy

Meaningful Activities for Learning & Creating

July 20, 2013 By Chelsey

Science for Kids: Sink or Float (with Free Printable)

Kids love discovering which items will sink or float ! It’s a great hands-on science activity for kids of any age and really gets kids thinking and predicting. Here’s how we set up our sink or float science project, as well as a free printable kids can use to record their observations.

Follow our Science for Kids Pinterest board!

This experiment was actually initiated by Lucy herself! She had approached me one day and asked if I could help get her a container of water to test out some objects she had collected.

Kids are naturally curious about floating and sinking, and this science activity provides the opportunity for children to make predictions and observations about floating and sinking with minimal help.   (This post contains affiliate links.)

Materials for Sink or Float Science:

• Large container filled with water
• Objects collected from around the house
• Free printable recording sheet  (optional)

• Walk around your house with your child and collect items you’d like to test out. (We collected these things: bristle block ,  plastic toy, crayon, cork, a spoon, and a rock.)
• Fill a large container with water. (We used a large plastic bin.)
• Find a place to conduct the science experiment where your child can easily reach the bin and where you don’t mind a bit of water possibly getting out.
• Have your child choose one object at a time.  Do you think it will sink or float? Why?   Have your child place the object in the water and observe what happens. (Optional: Record the result on the recording sheet. You can have your child draw a picture or write the name of the object or model writing and drawing the object yourself.)
• Repeat this for all the objects.
• Why do you think some objects floated and some sank? Is there anything the same about the objects that floated? How about with the objects that sank? 

Lucy had so much fun with this! It was fun to sit back and watch her excitement and curiosity grow as the activity went on. At one point she even came up with a new question, “I wonder what will happen if I push the floating things down to the bottom. Maybe they will stay there.” She discovered they still floated right back up!

• We took our experiment outside. That way there was no worry about a mess being made.
• I left this outside for a few days for the kids to experiment with on their own during play time.
• This would also be a fun center in a school classroom!

Want to go even further?

Even more activities to inspire creativity and critical thinking for various ages.

• Fill up a giant backyard pool with water and do this experiment with larger items.
• For older kids, introduce the terms density and buoyancy to explain what happened.
• Place an orange in your container of water to see if it floats. Peel the orange and try it again. What happened?
• Try the Floating Egg experiment found on Tinkerlab.
• Do our Dancing Raisin science experiment.

Find more STEM activities in our ebook! Learn more about it here , or b uy it now here !

• Collaborate

Little Scientists at Home: A Sink or Float Preschool Activity

One of my absolute favorite things about being a preschool teacher is doing science experiments with my students. To an outsider, it might seem like these activities are just silly fun. But, in actuality, there is a whole lot of meaningful learning going on. In this blog post, I share a simple sink or float preschool experiment. Additionally, I provide a free printable set with several resources–including a STEM design challenge extension activity. (I’ve designed everything so it can all be easily done at home!)

First, A Little Background On STEM

Before I begin, I quickly want to discuss STEM. You’ve probably heard the acronym before (especially if you’ve been browsing online for entertaining activities for your little one.) But, what does it mean? STEM stands for science, technology, engineering, and math. Sometimes it’s referred to as STEAM. In that case, the ‘A’ stands for art. It’s been an important part of education in recent years. Additionally, there has been a push to integrate these subject areas into many aspects of teaching and learning.

According to Britannica.com, “STEM emphasizes collaboration, communication, research, problem- solving, critical thinking, and creativity, skills that students need to be successful in today’s world regardless of specific interests or career goals.”

So what does that mean at the preschool level? To put it simply, teachers and caregivers should provide young children with opportunities to explore these subjects to help prepare them for the future.

NAEYC states, ” Research shows that giving children exposure to quality, hands-on STEM learning opportunities is so important and familiarity with STEM concepts early on is a key predictor of children’s school success.”

Therefore, it’s fair to say that the best time to introduce these types of activities is in early childhood.

The Scientific Method

Believe it or not, scientific exploration isn’t a foreign concept to young children. In fact, they actually begin to engage in this process naturally starting in infancy. The Early Childhood Learning & Knowledge Center (ECLKC ) does a great job explaining this:

“Infants and toddlers are natural scientists! They explore physical, natural, and social science anywhere and everywhere. They observe, are curious, and investigate to find out more about their world. They gather information as they solve problems. They communicate the results of their explorations through babbling, laughing, crying, physical gestures, facial expressions, and words.”

I give my preschoolers a more formal introduction to the Scientific Method at the beginning of each school year. This way they have more familiarity with this process to help better prepare them to reflect on their learning. Above all, I want them to understand that they are “little scientists” when they investigate and experiment.

As an aside, here’s a great video from FreeSchool that explains the Scientific Method in a kid-friendly way so you and your little one can watch it together!

Getting Started with STEM

It might seem overwhelming to come up with ideas for incorporating STEM at home. But, it doesn’t have to be. Let’s say my students are learning all about the life cycle of pumpkins at school. During that particular unit, I’d make sure to provide hands-on learning opportunities to teach literacy, math, and science skills using pumpkins. For instance, we might dissect pumpkins to explore what’s inside. We might also measure and weigh them. Finally, our classroom library would be stocked with books about pumpkins. All of this is arranged so that children can gain new knowledge or extend what they’ve previously learned.

With that said, reading books is an easy way to make STEM connections at home too. Think about it like this…books often have characters who are facing a problem that needs a solution. Therefore, they serve as a perfect jumping-off point for STEM learning because one of the first steps in the Scientific Method is identifying a problem. I should note that the books themselves don’t necessarily have to be science texts. Ultimately, they just have to have a theme or story that connects to the activity or experiment in some way.

Sink or Float Preschool Book Suggestions

Going back to the idea of problem-solving, I typically read “The Gingerbread Boy” to my class before doing this sink-or-float activity. In this version of the classic tale, the gingerbread boy gets gobbled up by the fox as he attempts to cross the river. Therefore, I tasked my students with the challenge of designing a boat that would have protected him and gotten him to the other side safely.

Here are some age-appropriate books you can tie into the concept of sink or float.

• The Gingerbread Boy by Paul Galdone
• Who Sank the Boat? by Pamela Allen
• Mr. Gumpy’s Outing by John Burningham

Sink or Float Preschool Activity

Now that we have reviewed the Scientific Method and book options, it’s time to jump into the experiment. First things first, I’ve created a free printable set with additional resources to help you at home. Moreover, it provides everything you need to easily do this sink-or-float preschool activity with your little one!

• Sink/Float Object Predictions Page (1 blank & 1 with suggestions)
• Vocabulary/Sorting Word Cards
• STEM Boat Challenge Directions
• STEM Boat Challenge Journal Page

What You’ll Need:

• free printable set
• reusable material such as tin foil and/or popsicle sticks
• various small objects like paperclips, bottle caps, marbles, rubber balls, rocks, etc.
• a large container filled with water
• small toy car or figure

Once you have your materials ready, then you can begin! Here are my suggested steps to follow:

First, have your child explore the concept of sink or float by placing a small toy or object in the water. Then let them make guesses on their prediction sheet about what will happen when various other objects are placed in the water.

Second, use your vocabulary word cards to make two columns: one for sink and one for float. Then have your child sort the objects based on what they observed during their exploration. They can place each object under the correct category/column.

Third, extend their knowledge by having them build/engineer their own boat using the reusable material of their choice. Ask them to make a prediction about what the boat will do on their journal page. Then let them test it out in the water. Does it sink or float? If it floats try adding small toys or objects to see if their design can withhold additional weight. If it doesn’t float ask your child to problem-solve and reengineer their boat. This is also a great point to integrate technology. Your child can take photos or videos of this design and testing process.

Fourth, once they are done experimenting have them reflect on their experience by filling out the rest of their journal page.

In Conclusion

At-home STEM learning doesn’t have to be daunting. As we’ve seen here, this entire activity can be done using items you already have at home. Furthermore, not only does it introduce science and engineering concepts in a fun way, but it also allows children to develop early math and critical thinking skills while engaging in play.

Now talk to me! Is this an activity you will try at home? Do you ever incorporate other STEM projects at home? If so, what are they? Share them in the comments below.

Additional Posts with At-Home Activities:

• Early Math With Blocks: How To Teach Your Preschooler Important Skills At Home
• How Music And Movement Promote Development In Preschoolers & How To Encourage This Growth At Home
• Free Activities For Preschoolers At Home

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Comments 22

Great ideas to get children involved and enjoying science!

Hi Sally, my daughter is very curious about everything, and it’s always great to have new activities to do with her on the weekends. This sink or float activity looks totally doable and doesn’t need too much to get started. Thanks for sharing this!

Yes and you can use items you already have at home so it’s even easier!

Amazing post. Very good idea for STEM activity

My kids love to do sink or float of anything that they can see around the house. Sometimes it’s messy but I know they can learn. Story telling can be a great idea for learning too.

It’s even something you can do in the bathtub so there’s less clean-up!

This sounds so fun and easy! My son loves to do experiments, so I will have to try this with him next. Thanks for sharing!

So easy to do! You can even do it during bath time!

Great idea with the boat. I’m definitely going to try this with my 4 year old daughter.

My preschool students have such a fun time with this. Please let me know how your daughter likes it.

My preschooler would LOVE this experiment! It’s so fun for them to try it out.

Please let me know how it goes!

Love this! Such a great post!

Thanks so much for your comment.

My daughter loves sink and float! We set up a little table with a water basin for her to explore independently. She puts objects in the water and sorts the objects by if they sink or float. It’s so great for little ones! I also found this really cool idea to play sink and float with fruits, to see which ones sink and float. We learned that oranges with their peel still on float, but with the peel off, they sink.

What a great idea! We’ve got to try that idea with the fruit! Such a fun extension activity!

This is such a fun idea and I am going to try this at home with my son for sure! 🙂

Wonderful! Please let me know how it goes! 🙂

Very cool! Children are natural scientists and I love writing for this very curious age group. In fact, I wrote a book on this very topic: Sink or Float 🙂

Thank you for your comment, Vijaya. I certainly agree. They are so very curious. That makes them even more fun to work with!

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Toddler and preschool activities

Written by Nadia T • Feb 8, 2024 • 4 Comments

Sink Or Float Experiment + Worksheet

This sink or float experiment  for kids is a great way to learn about weight, buoyancy, and density. Children will predict whether the object will sink or float in water and then can write their prediction on the free sink or float worksheet.

We LOVE doing science experiments for kids , and while this activity is geared towards kids 3-7 years old, it’s fun for a large variety of age groups. This is because the older they get, the more “creative” they’ll get with the items that they want to use to sink if they sink or float Related: Have you tried making Ice Cream In A Bag ?

Table of Contents

If you’re looking for a way to add some interesting aspects to home learning or even homeschooling, this is a fun experiment for the kids. You just need to gather up some simple household items and have your child look at them and make their predictions.

Once they get the hang out of it, they’re going to be using this reference in their everyday lives. Maybe the next time you go swimming, they’ll ask if they’ll sink or float when they jump in the pool? Isn’t it great how everything learning can be used easily in everyday life?

You’ll find that a simple Science experiment such as this sink or float experiment is an easy way to get the kids working together, without even really trying.

Why do objects sink or float?

1. Density : Density is a measure of how much mass is contained in a given volume. Objects with greater density than water will sink, while those with less density will float. For example, metals like iron are denser than water, so they sink.

2. Buoyancy : Buoyancy is the upward force exerted by a fluid (in this case, water) on an object immersed in it. This force opposes the weight of the object. Objects that are less dense than water displace an amount of water equal to their weight, causing them to float. Objects that are denser than water displace less water than their weight, so the buoyant force is less than the object’s weight, causing it to sink.

3. Shape and Volume : The shape and volume of an object also play a role in whether it sinks or floats. Even if an object is denser than water, it may float if it has a shape that allows it to displace enough water to generate buoyant force greater than its weight. This is why some boats, made of materials denser than water, float—they are designed to displace a large volume of water, creating enough buoyant force to keep them afloat.

Materials required for the sink or float activity:

You’ll need some materials to get started with this experiment. But also feel free to use other items that you have in your home as well.

• Water container/water table – we used the Ikea Flisat table.
• Objects to use. Choose a combination of items that will sink and those that will float. Items like a button, pencil, flower, crayon, apple, rubber duck, small ball, leaf, pear, etc.
• Printable (found at the bottom of this post, if you’d like to have your student record their predictions and results.)

Which objects sink?

• Metal objects such as paper clips, keys, or screws
• Rocks or pebbles used for sensory play or decoration
• Glass items such as marbles or small glass beads
• Some types of wooden blocks or manipulatives
• Playdough or clay sculptures
• Some types of plastic toys that are denser or heavier
• Coins or tokens used for counting or sorting activities
• Some types of art supplies like ceramic or pottery pieces

These items are usually denser or heavier than water, causing them to sink when placed in water during sink or float experiments or sensory play in preschool classrooms.

Which objects float?

Preschool classroom items that often float include:

• Rubber or plastic toys (such as ducks, boats, or figurines)
• Foam letters or shapes used for learning activities
• Plastic building blocks or manipulatives
• Empty plastic containers or bottles
• Corks or stoppers from various art or craft supplies
• Styrofoam cups or plates used during snack time
• Floating bath books or water-friendly storybooks
• Some types of crayons or markers with plastic casings

These items are typically lightweight and have a lower density compared to water, allowing them to float easily during sink or float experiments or water play activities in preschool classrooms.

Set up the sink or float experiment

Since there is water involved, you might want to set it up outside or on your porch, but if you don’t have that option, don’t worry. You can easily lay down some towels on the floor and have this experiment inside, too.

Once you have gathered up those items, it’s time to get started. (Don’t forget to print out your worksheet below!)

The easiest way to get started is to have your child pick one item, feel the weight of it, write down the item on their sheet and then make a prediction about whether or not it’s going to sink or float.

Then, once they put it into the water, they need to follow that up by recording the correct action that happened.

Talk about this sink or float experiment and why they think that some things are sinking while others are floating. It’s a great way to extend the learning time and to have them active and involved as well.

Questions to discuss after the experiment:

• What did all the items that floated have in common? What about those that sunk?

Did you know that oil has a different density from water? We explored this concept in our fireworks In a jar oil and water science experiment

Other ways to use this sink or float experiment

Once your child gets the hang of how it works, you can even have it to where they’re using two items at the same time and trying to guess which one will sink faster than the other.

Or, have your children take turns and use creative play as though they’re scientists in a lab.

Let them use their imaginations as well when using this science activity!

Make sure to talk about items that are safe (and not safe to put in water) before they go exploring to find more items that can they can use in the sink and float experiment.

(and just in case, be right there with them supervising so that they don’t decide to test out your cell phone to see if it sinks or floats!)

Here’s what students will learn when engaging in sink or float activities:

1. Observation Skills : Preschoolers will learn to observe the behavior of different objects in water. They will notice whether the objects sink to the bottom or float on the surface.

2. Predictions : Engaging in sink or float activities encourages children to make predictions about whether an object will sink or float before testing it out. This helps develop their ability to make educated guesses based on prior knowledge and observations.

3. Cause and Effect : By testing various objects in water, preschoolers begin to understand the cause-and-effect relationship between an object’s properties (such as weight, shape, and density) and its behavior in water.

4. Classification : Students will learn to classify objects based on whether they sink or float. This helps them understand basic concepts of categorization and sorting.

5. Critical Thinking : Sink or float activities promote critical thinking as children explore why certain objects sink while others float. They begin to ask questions and seek explanations, fostering a curious and inquisitive mindset.

6. Comparing and Contrasting : Preschoolers will compare and contrast different objects based on their sinking or floating behavior. This helps them develop skills in recognizing similarities and differences.

7. Problem-Solving Skills : When an object behaves unexpectedly (e.g., a heavy object floats), children engage in problem-solving to understand why it occurred. This encourages them to think creatively and analytically to solve the puzzle.

8. Language Development : Engaging in discussions about sink or float activities enhances language development. Children learn new vocabulary related to buoyancy, density, and properties of objects as they describe their observations and share their findings with others.

9. Hands-On Exploration : Sink or float activities provide hands-on learning experiences that are essential for preschoolers’ cognitive and sensory development. Manipulating objects in water stimulates their senses and enhances their understanding of the physical world.

10. Curiosity and Wonder : Most importantly, sink or float activities spark children’s curiosity and wonder about the world around them. They become excited about science and discovery, laying a foundation for lifelong learning.

Don’t forget to print out your free worksheet printable here!

WHERE TO GET THE ACTIVITY

GET THE SINK OR FLOAT ACTIVITY HERE

Check out the Pop Rocks and Soda Experiment too!

Tips for this Sink and Float Experiment

Build your child’s confidence by letting them take over and fun the show. After learning for a short time, they’re going to be ready to take over and experiment.

Step back and become their “assistant” in the science lab. That way, they’re in charge of the experiment and you’re just there to help them as needed.

Having a towel handy to dry off items is also a good idea. Saves a big mess from happening!

Once your child has gone through all the items, use some math skills and count up how many items sunk versus how many items actually floated.

Don’t forget to change up the items and let them do this sink or float experiment over and over again!

Like Science activities for kids ? Check out these as well:

• Water In A Bag Pencil Experiment – Water Experiment for Kids
• Rain Cloud In A Jar Science Experiment
• Walking Water Experiments For Kids
• How To Make A Lava Lamp Experiment
• Baking Soda Volcano Experiment

More Science Experiments

Nadia is a mom of 4, with a passion for making childhood education fun through play. She encourages parents to spend quality time with their kids through fun kids activities and enjoys art, traveling, and doing activities with her children.

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Reader Interactions

August 29, 2021 at 10:37 am

Just came across this and it was just what I needed. Can’t wait to use it with my primary classes. Thank you for creating it and I look forward to seeing all your TPT items.

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STEM Experiment: Scientific Method Float or Sink Activity

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Oh the scientific method! Such a structured way to exploration but so helpful when taking on a big scientific project. Scientists and researchers use this method when trying to answer questions about our world. Following the scientific method allows researchers to have a guide that helps them organize all the information. Because let’s face it, nowadays the information at our fingertips is so huge! With this STEM experiment, you can help your children get an understanding of using the scientific method in a fun and educational way.

** Check out our Simple Science Project For Kids: Float or Sink for a simple play-based version of the Float or Sink experiment! Perfect for younger kids or if you are looking for a less structured activity. **

Having a tool like the scientific method is very useful. And introducing it to your kids will help them with problem-solving and analytical skills. It will give them a way to structure their thoughts when problems arise. It also shows them to take their time to think about the problem and analyze different perspectives before choosing the best solutions.

Some Background Information

The scientific method is used by scientists to structure their research and make the process of discovering something more efficient and effective.

The steps to the scientific method are the following:

As you can see, there are many steps before starting any experiment. By researching and writing down your hypothesis first you will be able to set up the perfect experiment to answer the question. You will also have some background knowledge that will help you when doing the experiment.

STEM Experiment: Let’s find out the Answer to…

The question.

So here is a question for your children:

Why do you think things float or sink?

They probably have some ideas and answers for this. Encourage them to write down their original thoughts so that you can compare them once you are done with the STEM experiment.

Here you can find a free printable to fill out as the experiment goes on.

Time to Research

Research is usually done by reading and reading and more reading of scientific papers, journals and relevant material. We are not going to do this 🙂 We will move the research along by asking our kids some questions. So let’s get your kids brain to work a bit:

• Think of objects that float/don’t float, what are they made of? How big are they?
• Do you float in water? Can you make yourself float more or less? (By filling your lungs with air and holding your breath you will float more)
• Show them a list of materials, do you think materials matter?
• Show them different sized objects or images of objects, do you think size matters?
• What other things do you think affect the ability of an object to float or sink?

Write down a Hypothesis you want to test

Now that you have brainstormed about why an object floats or not you can make a hypothesis or more than one! But first, what is a hypothesis?

• A hypothesis is an idea or explanation for something that needs to be proved
• A hypothesis tries to answer the question of your research (in this case, why do things float or sink?)
• A hypothesis is proved through experiments and testing

Some ways you can express your hypothesis:

• Things made out of _______ float/sink
• Things that are ___________ float/sink
• Floating depends on ______________

Time to test those Hypotheses

Once you’ve made a hypothesis, ask your child how you could test it. Here are a few examples of experiments you could do with them but feel free to come up with your own!

First step in any experiment is to gather the materials you are going to test and any tools you might need. For any experiment you are going to need:

• Objects to test (different sizes, materials and shape)
• Water, in a bucket, in the sink, in the bathtub, in a small outdoor pool
• Paper and pencil to write down your findings

Ways you can experiment and make your children think about the hypotheses:

• Categorize the objects you have collected and test their floating ability by pairs:

           ○ same material, different size

           ○ same material, different shape

           ○ same size, different weight

• Get plastic containers and fill them with different materials and test the floating capabilities, for example:

          ○ empty container

          ○ container filled with cotton (what happens when cotton gets wet?)

          ○ container filled with sand

          ○ container filled with water

          ○ container filled with sticks

          ○ container filled with coins

          ○ container filled with stones

• Do the same with a glass container

There is a list of materials and object ideas in the guide for inspiration. Let them experiment and play 🙂 there is no rush to finish the activity! Don’t forget to write down your findings so you can analyze them later!

Let’s analyze those Resultats

Now it’s time to look back on your STEM experiment and the results to see if your hypothesis was correct. You can ask the hypothesis back in question form and see if the results support it! Other questions you can ask to discover why certain objects float:

• Does wood/plastic/metal/stone float?
• Does shape or weight matter?
• What containers could float? Which ones would sink? What was inside of them?

Conclusion Time

So did you find out why things float? Did you test your hypothesis? Did you get some fun ideas about other things you could test with this method? Did more questions pop up as you experimented? Welcome to the STEM world! The questions never end 🙂 and this is oh so important for your children to experience. How to answer questions using the scientific method is a must in the STEM world. If you want a more detailed answer to why things float you can download the printable guide, there is an explanation at the end. But I’m sure that you will have a pretty good idea about the answer from all that scientific experimenting you will do 😉

So to finish up the activity you can talk about what you discovered and if there are more things you would like to research together. If you have any topics you would like me to cover just comment below and I’d be happy to write a post about it in the future. I hope you enjoyed this activity and had fun experimenting and discovering how our world works.

For more information about STEM and how to transform your STEM activities at home, check out these posts:

• 5 tips to transform STEM activities at home
• What is STEM and why is STEM learning important?

Check out other fun STEM activities to sneak in some STEM learning:

• STEM activity: Build a pyramid and learn about shapes
• STEM project: Engineer a house out of natural materials
• STEM challenge: The Tower of Random Things
• STEM water play: 8 fun activities to try this summer
• STEM Road Trip Experiment

Happy STEM learning!

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Float and Sink Activity for Preschool Pre-K

Try this outdoor learning activity to help kids explore and discover which things float or sink. By freely exploring with materials, children learn the scientific process. They form their own questions about why something happens, and test out their own theories.

Materials Needed: Tubs of water (one for every pair of children) Small items that will float Small items that will sink Towels

Set Up: Fill tubs with water. Gather float and sink items, and sort them into bowls or containers.

Procedure: Give each pair of children a tub of water, and tell them they are going to test several things to see if they will float or sink. Pass each child a bottle cap, and ask them to make a prediction whether they think the cap will float or sink.  Ask them to place the bottle cap in the water to see what happens. Have children test each of the items in the same manner, making a prediction first, then testing them. Do not pass out all of the items at once; instead, pass them out one at a time, randomly. Each child gets their own item to test in the water, but each pair of children shares a tub of water.

Examples of things that sink: Pebble Penny Marble Toy fish (like a math manipulative fish)

Examples of things that float: Bottle Cap Feather Unifix cube Small piece of paper

I usually do this activity during my Ocean Theme  (find more activities here).

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Fantastic Fun & Learning

Fun learning activities and things to do with kids

Sink or Float Science Activities

By Shaunna Evans 6 Comments · This content may contain affiliate links.

We’ve been incorporating a lot of open-ended explorations into our preschool activities. These sink or float activities are an engaging way for kids to explore the properties of different materials. They are great science investigations for toddlers and preschoolers.

I love how Ashley from Life with Moore Babies encouraged her kids to collect  their own objects for this  Does it Float or Sink?  activity.

These  Sink or Float Activities for Toddlers  from Mom Inspired Life include some great objects that I hadn’t thought of experimenting with before.

In  Science for Kids: Sink or Float , Chelsey from Buggy and Buddy helps her daughter put together her own science investigation along with a great free printable.

This Sink and Float Water Play with Natural Materials is perfect for toddlers on hot summer days.

This Does it Sink or Float? – Pirate Style activity is perfect for little learners.

Teach your kids about surface tension in this Make a Paperclip Float experiment.

This Will it Sink or Float? Is a great easy science experiment your kids will love.

This Salt Water Density Experiment For Kids is a fun twist on the classic sink or float experiment. Extend this experiment by testing to see if there is a difference between raw and and hard-boiled eggs in this egg floating science experiment .

Use leftover fruit to test these Fruity Boats .

This Garden Sink or Float Activity will be an instant hit with your kids.

FREE PRINTABLE SINK OR FLOAT RECORDING SHEET

Design your own Sink or Float Science Experiment with this free printable recording sheet.

Gather materials and experiment to see whether they sink or float. Then recording the results by drawing or writing in the free printable sink or float recording sheet.

 Complete the form below to get your free printable sink or float recording sheet.

More Math and Science Activities with Fizz, Pop, Bang!

Fizz, Pop, Bang! Playful Science and Math Activities is designed to bring hands-on fun to math and science play. It’s full of engaging and powerful learning opportunities in math and science, shared through ideas that incorporate art, play, sensory learning and discovery, for a whole-brain approach.

It includes 40 educational projects and 20 printables including a set of build-your-own 3D shape blocks, engineering challenge cards and a range of math games.

Learn more about Fizz, Pop, Bang! or you can buy it now !

Reader Interactions

March 29, 2022 at 3:37 pm

We love all your hard work. It makes learning fun!! Thank you.

August 14, 2013 at 8:03 am

My son loves sink and float! Would you share these today if you have a moment? I would love to see you over there!

August 17, 2013 at 9:00 pm

Would love to share. Thanks for the invite.

August 13, 2013 at 4:18 pm

Thanks for including our experiment!

Mary Catherine

August 13, 2013 at 12:52 pm

Shauna, what a lovely collection of open-ended science! As always, I love discover & explore and FFL!!

August 17, 2013 at 9:08 pm

Thanks, Mary Catherine!!

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Sink or float

Sink or Float!

This activity allows children to explore a variety of materials and test to see if they will sink or float. Children use their critical skills, create and test their hypothesis and discuss the end result of the experiment. This may seem like a simple learning opportunity but with the right questions and materials, can be turned into an engaging and fun learning opporutnity.

• Large container with water and different objects and materials (man made and natural)
• Involve children in choosing what materials they would like to test

Learning Goals

• Children experience various textures, weights, materials and can see which of the materials float and sink.
• Prediction and logical thinking, increasing children’s confidence in their ability to think for themselves.

Process Description

Children collect various materials from the natural and man-made environment. Materials can include coins, leaves, paper, wood or any material they find interesting. When the materials have been collected, ask children to predict if they will sink or float when placed into water and record their assumptions.

The items children think will float, should be placed on one side if a table while the items they think will sink, should be placed on the opposite side. If you have labels (i.e. sink / float), put the relevant materials under their relevant label.

It’s time to test! Start placing the objects into the water to see if they will float or sink!

Engage in discussion! What happened? Was your assumption correct? Why/why not?

If you find that children are interested in science or want to introduce further water-based science experiments to the children, check out our video on exploring with  water clouds .

Reflective questions

• Did all children benefit from this? How can I aid all children in their learning?
• I would like to improve…
• What additional resources could have enhanced children’s learning?

Looking and responding

Start by asking the children to describe what they see. Draw attention to specific details that link into curriculum goals. Why did this float but not this? What is the difference between these two objects (size, weight, density)?

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My Mundane and Miraculous Life

Sink or Float: Our Very First Science Experiment for Preschoolers

October 14, 2014 By Julie 5 Comments

Gather up  a bunch of objects that will… get this… either sink or float. I know. Brilliant.

Then get a tub of water.

Don goggles (or googles as my son calls them).

I promise that’s just water. Oh my!

I wanted to introduce Loopy to the very basic basics of the scientific method. So we whipped up a chart to track our predictions and outcomes. It was all very exciting!

Um, maybe I should laminate it next time.

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I loved watching his wheels spin as the more objects we tried, the better he became at accurately predicting the results.

Eventually Loopy concluded that lighter objects float while heavier objects sank. Then I purposefully grabbed object to debunk that theory. When I started explaining water displacement, he decided he’d rather stick his head in the water.

“Cool it, Einstein!” I said to myself and let him play.

Here’s his all the objects we experimented on, sorted by whether they sink or float.

This was such a good first science experiment that Loopy wanted to do it again the very next day!

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Julie is a frazzled mom of three tornadoes. As a dorky second-generation homeschooler, she writes about learning and play, natural living, special needs parenting and matters of the heart. She serves an astounding God that radically saved her.

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Anne at Left Brain Craft Brain says

October 20, 2014 at 12:27 pm

This looks like a really cute way to teach the scientific method. Very fun!

October 20, 2014 at 1:47 pm

Thanks Anne! I just LOVE your site! Honored that you stopped by!

[…] experiments are pretty new to our home preschool. Our first experiment was a HUGE success so Loopy and I were both pumped to try again. We’ve been studying astronauts and space this […]

[…] Will it sink or float? – We did this while Rowen was napping. Damien picked ten random household objects (mostly toys) and we made a chart, then we experimented to see if the item sunk or floated in a bowl of water. Damien enjoyed it but mostly enjoyed playing with all the items in the water afterward! […]

[…] Sink or Float Experiment […]

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Tot School: Sink or float: an amazing toddler Science experiment

Anyone else a Blippi fan? We are, especially of his songs. Blippi has a few videos working on the toddler science experiment: sink or f loat skill, so when I set this up at home, Manu was too excited to test this out for himself.

The sink or float toddler science experiment consists of gathering a few materials and dropping them into a bucket of water . Then seeing (or guessing ahead of time) if they will sink to the bottom or float and stay on the surface.

Supplies for Sink or Float toddler science experiment

• Bowl or container (preferably a clear one)
• Toys and household things that can get wet

Recommended age for this activity

We did this activity at 30 months old and kept it very simple. Just seeing what things sink or float.

This activity can be set up to be more challenging for older kids; I know in this activity is very famous during kindergarten, where kids have to complete charts and graphs and answer more questions.

Depending on your child’s age, customize the activity to make it challenging enough but not too challenge that they will get discouraged from participating.

What does sink or float teach toddlers

This sink or float experiment will teach your child the concept of buoyancy and density. Through their observations, they’ll learn that  buoyant objects float and dense objects sink .

Of course, they won’t call it by that name but they will understand the concept about each one.

How to play sink or float

I like to involve my child as much as possible when doing activities, and this one was no different.

I provided a bowl and a pitcher of water; Allowing him to be the open pouring the water into the bowl. Pouring is also an activity I like for him to master, so involving him in this part is part of the fun.

And yes, I crossed my fingers that he didn’t pour it so fast that the water would completely miss the bowl and fall on the floor. He did awesomely, so then the fun began.

Prepare for the mess

This activity uses a lot of water. Make sure you prepare for the mess. Either place a beach towel under your bowl or so this activity outside.

Another mess-free option will be to do this activity in the bathtub.

Will it sink or float

Gather things that you can throw into the bowl. You can do this ahead of time, or you can walk around together and choose something that catches your little learners’ eye and discover together if it sinks or floats.

I’m very open to this allowing him to explore and throw in whatever he wants as long as it was safe, of course, and that the toy didn’t have batteries. We have ruined way too many toys that use batteries by him bringing it into the bathtub or pool.

Sometimes he chose things that were too big for the bowl, and even though I said “it won’t fit,” he needed to discover it by himself to believe me.

This toddler science experiment is al about that, experimenting. So be open-minded with the items that you choose.

Ask questions!!

At the beginning of the activity throw in the item into the bowl and then say what happened.

“Oh! It sinks!”

Keep going for a while, and then once you know you’re toddler seems to identify what is sink and what is float, then ask questions before the item is dropped.

Do you think the Playdough will sink or float?

View this post on Instagram Have you played the sink or float game? Well, actually is a science experiment and one of our favorite activities. I usually let Manu set up the whole thing form the beginning. I give him a pitcher of water and an empty bowl for him to pour h the e water into. Then we walk around and find different things to test out. Will it float? Will it sink? I let him pick what he wants to throw (as long as it can get wet and has no batteries) and this freedom lets him explore and learn. Who knew a bowl of water could be so fun! #2yearoldactivities #toddleractivities A post shared by Alexa | Kid Activities (@kidactivitieswithalexa) on Sep 28, 2020 at 2:58pm PDT

Blippi Sink or Float toddler science experiment VIDEO

RInse and repEat

Toddlers (well, actually all kids) learn through repetition. Repeat this activity several times throughout the week or month to ensure they understand the concept well.

Don’t stress if they don’t; after all, they will practice this to kindergarten. Focus on making it fun, engaging, and something to do together.

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Sink or Float? A Simple, Hands-on Preschool Experiment

Supplies for a Float and Sink Experiment

• Tub of water (or in our case a water table )
• Random object from around the house with varying densities

Instructions for a Hands-on Experiment in Density

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Recycled Boats – Sink or Float

September 16, 2019 By Emma Vanstone 1 Comment

Recycled boats are fun to make a great for exploring the concept of buoyancy or for little ones just very basic sink or float activity.

A sink or float experiment makes a great first science activity for preschoolers ( always watch them carefully around water ) and a fun first attempt at making a prediction or hypothesis for older children.

If you want to structure the activity like a real experiment you can also introduce the concept of variables where you only change one variable for each test. For example, use the same boat, but change the object inside. You can then follow that by using the same object but different boats and record the results.

What you need to make a recycled boat

Empty containers

Old magazines or newspaper

Double sided tape

Large container filled with water for testing

How to make a recycled boat

This bit is up to you! We made our recycled boats very basic, but you could make yours as fancy or simple as you want.

Red Ted Art has lots more homemade boat inspiration too!

Preschool floating and sinking science project

For younger children start by asking them to test different objects to see if they sink or float. Once they’ve tried a few ask them to predict whether the next one will sink or float. Empty ( and full ) water bottles, large stones, plastic or metal toys and pine cones are good things to start with.

The next challenge is to try to find a way to make an object that sank, float. One way to do this is to place it in a boat. Plasticine boats, aluminium foil boats or recycled boats like we made should work perfectly.

We had some lemons hanging around so made some lemon boats too, you can also make boats from melon, oranges, limes and other fruits with a thick skin. They float because the skin is full or air bubbles, which reduces the density.

Sink or Float – explore further

Find out how to make a lemon sink and why lemons float with this activity.

We love to theme our activities. Sink or float pirate style is always popular.

Keep it simple with a LEGO sink or float activity .

For older children discover why some objects float and some sink and find out how to make a ball that sinks, float!

For a slightly different sink or float experiment pour a layer of vegetable oil over water and try to guess which objects from a selection will float on each layer .

Last Updated on April 21, 2021 by Emma Vanstone

Safety Notice

Science Sparks ( Wild Sparks Enterprises Ltd ) are not liable for the actions of activity of any person who uses the information in this resource or in any of the suggested further resources. Science Sparks assume no liability with regard to injuries or damage to property that may occur as a result of using the information and carrying out the practical activities contained in this resource or in any of the suggested further resources.

These activities are designed to be carried out by children working with a parent, guardian or other appropriate adult. The adult involved is fully responsible for ensuring that the activities are carried out safely.

Reader Interactions

September 16, 2019 at 8:41 pm

I really enjoyed this experiment, and testing it out with my four year old daughter. We had fun constructing the boat and even though she did realize it, developing a hypothesis.

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The Global Montessori Network

• Sink and Float

This activity is designed for 3-6-year-old children. This science activity allows children to explore the concept of sink or float. 

The Objective of Sink or Float Activity

In this activity, children can play, experiment, and discover what types of objects float and sink in water and why during a hands-on activity.

Why Do Objects Sink or Float?

• Weight: The weight of an object is the measure of gravitational force acting on that object. Heavy objects sink, and lighter objects float
• Buoyancy: The buoyancy of an object placed in liquid measures the upward force of the liquid acting on that object. When the upward force acting on an object in liquid is greater than the downward force of gravity (or its weight), the object floats, and vice versa. 
• Density: Objects denser than water will sink, and objects less dense than water will float. 

Benefits of Sink and Float Activity 

This activity enables the child to promote scientific thinking, such as cause and effect, observations, comparison, reasoning, data gathering, experimentation, and evaluation.

• It helps in language development by introducing various objects that can sink or float.
• It develops the OCCI: order, concentration, coordination, and independence.
• It coordinates and controls hand-eye movement.

Material Required for Sink or Float Activity

• A large container filled with water
• Two containers to sort floating and sinking objects
• ones that float: feather, Lego, bath toy, crayon, ping pong ball, plastic utensil, pencil, etc. 
• Ones that sink: toy cars, coins, metal spoon, eraser, dry pasta, etc.
• Towel to wipe spilled water

How to Introduce Sink and Float Activity to the Child?

Bring the activity from the shelf and organize the material needed. Invite the child to perform the activity and differentiate objects that can sink and float in water. Ask them to sort the objects and put them in their respective containers. Demonstrate the activity slowly and carefully so that the child can see and understand each movement.

• Fill the container with water.
• Using tweezers, take an object from the basket and place one item into the water at a time.
• Ask the child, “does it float or sink?”
• Let the child observe whether it floats or sinks.
• Remove them from the water with the tweezers.
• Place the object into the corresponding labeled container.
• Repeat the exercise with every object.
• Talk about why some objects sank, and others didn’t.
• Discuss the weight, size, and material the object is made of and how this influences the floating ability. Let the children relate to the density, buoyancy, and weight of the object.
• This sensory experiment encourages children to be curious, observe closely, and notice patterns. 
• Clarify the doubts that a child may express.

Questions to be Asked to Children While Performing the Sink and Float Activity

• Look at the objects that sank. Do they have anything in common with one another? 
• Look at the objects that are floating. Do they have anything in common?
• What is the reason objects float or sink?

Variation of Sink or Float Activity

Materials required:.

• a pair of scissors, 
• Few coins or beads, 
• Bucket full of water

How to Introduce this Variation of Sink and Float Activity?

• Take the tinfoil and cut small squares out of the tinfoil shape then slowly put the cutout and float it on the surface of the water. 
• After that, place coins or beads one by one in the center of the foil.
• Keep placing coins one by one on the tinfoil until the tinfoil sinks to the bottom of the container. 

Questions to be Asked While Introducing the Sink and Float Activity

• What was the number of coins you could place on the tinfoil? 
• What is the maximum number of coins you can get by arranging the coins differently on the tinfoil? 
• Whether the shape of your tinfoil float is changed, how many coins can you get?

Fun Facts about Sink and Float Activity 

• The density of liquids varies as well. You can make a mixture of corn syrup, oil, and water by mixing them together. Since corn syrup is the densest, it sinks to the bottom. Because of its lightness, oil floats to the top of the container, whereas water is in the middle.
• An object’s shape can also affect whether it sinks or floats. When you put a ball of clay in water, it sinks immediately. However, Clay will float if it is flattened out into a raft shape.
• It is also possible for objects filled with air to float. Iron sinks into the water but a boat made of iron will float on water because of the air which is filled inside the boat.

Watch the video to learn more about the science behind the floating and sinking of objects. 

Related Video Resources

• Tilt of the Earth’s Axis
• Life Cycle of a Butterfly
• The Coming of Life

To watch more science video lessons, click here . 

Video created by: by Alejandra Jurado

• Why sink and float experiment is important?

The sink and float activity helps the child to understand the concept of buoyancy and density. They will learn that buoyant objects float and dense objects sink as they observe.

• What is the meaning of float and sink?

An object floats if its density is less than water. It means that the upthrust of water on an object is greater than its weight. Objects that have a density greater than water sink.

• Do things float better in salt water?

The ocean or extremely salty bodies of water, like the Dead Sea, are denser than freshwater, which is why some things float more easily there.