Hidden LEGO Men – 100 days of play

This easy science activity is great for learning about how some materials absorb water and some do not. It can also be used to demonstrate capillary action to older children.

Traditionally, paper flowers are used which open up in water, but we changed it a bit to reveal LEGO® Men.

Hidden LEGO® Men Science Activity

You’ll need

  • Different types of paper cut into squares. We used thin paper, thicker notebook paper and cardboard.
  • LEGO® men or other small toys.
  • Water
  • Tray

Instructions

Fold each corner of the paper into a triangle to look like the one below.

black sugar paper with the four corner folded up on water for a science activity

pink paper on water that has unfolded with a LEGO figure floating on top

Before we started, we looked at each type of paper and talked about which we thought would absorb water the most easily. My 6 year old thought the thinner paper would absorb more water faster than the cardboard.

floating

Why does this happen?

Paper is made of many fibres. As the fibres absorb water, they swell, causing the paper to expand and open up.

Different types of paper absorb water at different speeds. Thinner paper absorbs water more quickly, as it has thinner fibres.

Hidden toys - capillary action science experiment

Last Updated on March 6, 2025 by Emma Vanstone

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17 Comments

  1. Great idea! I loved playing with LEGOs in the water, but this will add a lesson to it as well. And then you can have the LEGO coast guard come to rescue the guys after the experiment is done!

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