Shelter Investigation: Which Materials are Waterproof?

As part of our 'Materials' topic in Science, we role-played being lost in the forest....it started to rain so we needed to build a shelter! 

Unfortunately, it wasn't actually raining the afternoon we carried out our investigation. However, we had people pour rain (water) onto different materials (with volunteers underneath) to find out whether or not they were waterproof and suitable to make a shelter with. 

First, we made predictions in class before using our outdoor learning time to test our predictions.

We found out that plastic and metal are waterproof, and that cotton and cardboard are not waterproof. Therefore, plastic and metal would be suitable materials to use to build a shelter.

Where have we got a plastic shelter on our school grounds?
What other material could be used to make a shelter? Think about what we have in our playground.