7 Quick and Easy Density Experiments for Kids

Why do rocks sink and leaves float? Does a balloon filled with water float above or below the surface? Do olive oil and water mix? Answer all your child's questions about density with this list of quick and easy experiments!

  • Visual aid of how to complete Cartesian Diver
    Cartesian Diver

    (Ages 5-11)

    Explore the science behind density and pressure with this DIY bottle diver. Make a scuba diver toy and watch it sink or float by squeezing the bottle.

  • Visual aid of how to complete Floating Fish
    Floating Fish

    (Ages 5-11)

    If you've ever been swimming, you know what happens if you stop moving. You start sinking! You can always spread out your arms and legs, but that only lets you float on the surface. So how do fish float in the water without rising up to the surface, or sinking down to the bottom? Let's investigate!

  • Visual aid of how to complete Liquid Hourglass
    Liquid Hourglass

    (Ages 5-16)

    This liquid hourglass relies on the density gradient between olive oil and water to help you keep track of the time! How long do you think it will take for the liquids to switch places?

  • Visual aid of how to complete Lava Bottle
    Lava Bottle

    (Ages 3-11)

    This fun science project that is guaranteed to impress! This is a cheap and easy way for your child to explore the nature of different properties in a super cool way. Talk about a groovy project!

  • Visual aid of how to complete Sink or Float?
    Sink or Float?

    (Ages 3-8)

    Will your toy sink or float? This experiment is fun for all ages.

  • Visual aid of how to complete Density Tower
    Density Tower

    (Ages 5-16)

    Density is a foundational concept in physics, which explains why boats float, rocks sink, and balloons fly away when you let them go! With just a few materials from home, you can conduct your own colorful density experiment, and see how this principle works firsthand. Check it out!

  • Visual aid of how to complete Brazil Nut Effect

    If a Ziploc® brand bag full of nuts is shaken, which pieces will end up at the top? You might guess that the bigger, heavier pieces sink to the bottom, but that’s not actually what happens! In this experiment, you will see the Brazil nut effect, where larger objects rise above smaller ones. This effect is named after Brazil nuts, which tend to end up at the top of mixed nut cans, but it can happen with all sorts of dry snacks (we’re looking at you, muesli and trail mix). In order to really see the Brazil nut effect in action, let’s experiment with something super small (like rice) and something much larger (like jumbo marbles).


Get inspired!