☰ Year plan · Science

Testing materials (2)

Week 15 · Unit 3 · 3.4 · 3 lessons
1

Which keeps water out?

Workbook 2: Topic 3.4, pp. 38–40
GoalDo a test to find out which materials are waterproof and record what you see.
New words
waterproof · does not let water throughobserve · to look closely and notice thingsdry · with no water on it
Explanation

Sara tests which materials would make a good rain cover. She lays a piece of each material on a dry paper towel. She pours three spoonfuls of water on each one. She waits one minute and then lifts the material and looks at the towel. If the towel is dry, no water went through, so the material is waterproof. She keeps the pieces the same size, the water the same and the time the same. The only thing she changes is the material.

MaterialPaper towel under it
plastic bagdry
foildry
newspaperwet
cotton clothdamp
Worked examples
plastic bagfoil
Under the plastic bag and the foil the towel was dry. Plastic and foil are waterproof.
Under the newspaper the towel was wet. Water went through, so newspaper is not waterproof.
cotton cloth
Sara predicted that the cloth would keep the towel dry, but the towel was damp. Her prediction was not right, and that is fine: the test helped her find out.
Class activity

Waterproof test (with an adult): lay pieces of the same size on dry kitchen paper: plastic bag, foil, newspaper and cloth. Predict first. Pour 3 spoonfuls of water on each. After one minute, lift each piece and look at the paper below. Record wet, damp or dry. Wipe up any spilled water.

Practice
1
Look at Sara’s table. Which two materials kept the towel dry?
2
Ravi tested three more materials. Which one would make the best tent?
MaterialPaper towel under it
woolly hatwet
rubber glovedry
paper bagwet
3
Name two things Sara kept the same.
4
Predict: will the paper towel under a piece of balloon rubber be wet or dry?
rubber