All lessons › Material matters › Lesson 3
Australian primary science · Years 3–4 · Lesson 3 of 6
Keep it dry
Inquiry question: Which material would make the best raincoat for a teddy?
Check practical materials
Fair testing
What students learn
Some materials are waterproof and others absorb water; this property influences their use.
Success criteria
- I can say what to change, what to observe and what to keep the same.
- I can test waterproofness fairly.
- I can explain which material suits a raincoat using my results.
Preparation and materials
Before this lesson: Students can record observations accurately (lesson 2).
- Squares 12 cm × 12 cm of: paper towel, cotton fabric, plastic bag, aluminium foil, felt, newspaper — 1 of each per pair (78 squares)
- Plastic cups — 13
- Rubber bands — 13
- Teaspoons or droppers — 13
- Jug of water — 3–4
- Paper towel for spills — 1 roll
Teacher setup
- Cut squares to the same size (12 cm × 12 cm, big enough to stretch over a cup).
- Half-fill jugs with water.
Safety and adaptations
- Wipe spills immediately to prevent slips.
Review your school policies and curriculum requirements before teaching.
How to investigate
The lesson sequence should leave pupils with evidence to interpret, not only an activity to finish.
- Complete the plan: change, observe, keep the same.
- Stretch a square over a cup with a rubber band.
- Pour 1 teaspoon of water on the middle. Wait 1 minute.
- Record: water in the cup? Material wet or dry on top?
- Repeat for each material, keeping everything else the same.
Teacher modelling prompt
Show an unfair plan: “Cotton gets 1 spoon of water, plastic gets 3 spoons.” Ask what is wrong. Then build the fair plan together: change the material; observe whether water reaches the cup; keep the same amount of water, square size and waiting time.
Record and explain evidence
Recording question: Which materials are waterproof?
| Material | Water in the cup? (yes / a little / no) | What the top looked like |
|---|---|---|
| ________________ | ________________ | ________________ |
Example recording headings; record actual observations, including inconclusive results.
Discussion prompt
Both materials passed the water test. What other property matters for a raincoat?
Provided example or reference data
Illustrative water-test observations (written for this lesson; not your own tests)
| Sample | Water and wait | Observation |
|---|---|---|
| Cotton fabric | 1 teaspoon; 1 minute | Fabric became wet; a little water reached the cup |
| Intact plastic bag | 1 teaspoon; 1 minute | Water stayed on top; none reached the cup |
| Intact foil | 1 teaspoon; 1 minute | Water stayed on top; none reached the cup |
Check the data source in the teacher lesson. Illustrative or fictional data are not measurements collected by your class.
Check understanding
What should pupils know? What does waterproof mean? Which material from today was waterproof?
Explain with evidence: Leo poured 1 spoon of water on cotton and 3 spoons on plastic. Why is this not a fair test?
Apply the idea: Which material would make a good towel: plastic, paper towel or cotton fabric? Use today’s evidence.
Teacher answer guidance and saved classroom work are available through the main lesson experience where supported.