Protect the pirate coins – waterproofing activity

This is an easy waterproofing activity with a pirate theme.

We painted one side of the coin so we could easily see if the coin was wet and placed 5 coins in each bag ( paper, cloth, plastic ) before spraying with water and then examining the coins.

pirate experiment



Washable Paint -optional, but helps the children to see if the coins are wet

Plastic bags

Cloth bags

Paper bags


Spray bottles


Ask the children to feel the bags and see if they know what material each is made from, before asking them to predict which will keep the coins driest.

Spray the bags one at a time with water. We checked the bags after 5 sprays and 10 sprays.

What do you notice? What happens if you shake the bag?


Our paper bag split after shaking and the damp coins fell out after just 5 sprays of water.

Waterproofing experiment

After 10 sprays to the cloth bag we could see paint starting to seep into the outside of the bag, indicating that the coins were wet.

waterproofing exepriment

The coins in the plastic bag remained dry. We gave the plastic bag some extra sprays and observed that the water beaded on the bag and then rolled off.

Waterproofing experiment

Extension tasks

Can you fill up the plastic bag with water? What happens? Can you think of an instance where this is useful?

Can you try other materials?

Can you think of any materials that might be waterproof?


Suitable for Key Stage 1

Everyday Materials

Describe the simple physical properties of a variety of everyday materials

Working Scientifically

Observing closely, using simple equipment

Performing simple tests

Using their observations and ideas to suggest answers to questions

EYFS – Early Learning Goal

The child knows about similarities and differences in relation to places, objects, materials and living things. 


Related posts

How waterproof is it?

Waterproof a pirate ship

Post Your Thoughts