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Science fun with under 5s!

Sometimes we think that our littlies are too young to understand science. But it’s not just the big school kids who get to have all the fun: we have a great experiment to encourage scientific thinking in your little ones.

Water displacement

Water displacement was first used as a method for measuring solid objects that were shaped irregularly. Essentially it means that we can find the volume of an object by how much the water in a jar moves when it’s placed inside. Remember that volume is a different measurement to weight – so light, but large objects will have the same volume as the same sized object in a heavier material.

This is a very easy experiment to do with young children in particular, because it’s an experience they already know of (when they get in and out of the bath, the water moves up and down). It’s also super cheap and easy to do, and even if you don’t have the time to spend doing the following experiment, you can still take the time to show them the next time they have a bath. Hop in with them to show them how much a larger object/person displaces all that water!


•    A large, transparent container (jars with large openings work best)

•    Tap water

•    A permanent marker

•    Various sizes of stones or small toys


1.    Half fill the container with tap water.

2.    Get your little one to draw a line where the water level is.

3.    Ask them what they think will happen if you place one of the small stones/toys inside the container – why do they hypothesise this? Encourage thinking about other experiences they’ve had: if we’ve seen something occur many times, we can rightly assume that it will behave the same way again.

4.    Test the stones/toys, keeping an eye out for the water displacement.

5.    Talk about why this might be happening and why it might be different depending on the size of the object.

6.    Explain water displacement, showing it to them whilst you’re both playing.

7.    Let them go nuts: see how high you can both make the water level rise with water displacement by placing all the stones/toys inside!

If you’re in the Christchurch area, then come join us at the Under 5 Fest – Celebrate Science through Play! More information is available here: www.under5fest.co.nz.

Science Alive is exclusively providing at-home science experiments to Family Times. For more, visit Science Alive’s blog at www.ScienceAlive.co.nz.

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