Why does it Float? (Density for Kids)

Kids will have fun learning about what floats with this fun unit exploring mass, volume, density, and more with four different fun, science projects for kids.

Start out by reading:


Now let kids try floating different objects in a tub of water. I suggest using this free printable with suggestions as well as space for kids to write their prediction and the answer.

does it float science experiment for kids

Density for Kids

Now ask kids, what is heaviest - a pound of feathers or a pound of gold?

The answer is they weight the same - they both weight one pound.However, the amount of space the feathers take up would be greater as you'd need more feathers to make a pound. The density of the gold is higher than the feathers.

Basically, density is how compact an object is. Put another way,
density = mass of an object (how heavy it is) / by its volume (space it takes up)

Understanding Mass and Volume

Mass and Volume Science Experiment for kids

So what is mass and volume?

Take 3 identical boxes (could be mac and cheese, jello, corn bread, pasta, etc.) and fill them with different things so that they will have different weights.
  • the volume (or amount of space for each of the boxes) is the same for each of them
  • the mass (weight of each box) is different

Watch this short clip to help it really click with the kids:

Density Experiments for Kids

Help kids understand this principal with these 2 simple experiments:
density experiment for kids
  1. Aluminum Foil - Start by only slightly wadding a piece of aluminum foil and try to float it on water. Now make a second ball using the same size of aluminum foil but this time make it into a tight ball and see what happens.  The density of the second ball is greater so it will sink more than the first one.
  2. Ice and Water - Show kids that ice floats. But wait....ice is water? Put water in a paper cup and make a line on the side to show the level of water. Now put the cup in the freezer until freezes. The water expands as it freezes. Now even though the mass (weight) is the same, the volume (space it takes up) is different so the density of the ice is slightly less than the density of water.

If you are looking for more homeschool science units:

Beth Gorden
Beth Gorden

Beth Gorden is a homeschooling mother of six who strives to enjoy every moment with her kids through hands-on learning, crafts, new experiences, and lots of playing together. Beth is also the creator and author of 123 Homeschool 4 Me where she shares 1000+ free printables, creative homeschool lessons, crafts, and other fun ideas to help preschool and homeschooling families have fun while learning and exploring together.