All lessons › Rain, seasons and Country › Lesson 3
Australian primary science · Year 4 · Lesson 3 of 3
Catch the rain
Inquiry question: Does a wide container catch deeper rain than a narrow one?
Check practical materials
Fair testing
What students learn
A rain gauge measures the depth of rain in millimetres. Any straight-sided container left in the same rain collects about the same depth, which is why rain measurements from different places can be compared.
Success criteria
- I can measure water depth in millimetres with a ruler.
- I can keep the test fair by putting both containers in the same “rain”.
- I can explain why a rain gauge measures depth, not amount of water.
Preparation and materials
Before this lesson: Students know rainfall is measured in millimetres (lessons 1 and 2).
- Clear plastic drink bottles with straight sides (1.25 L or 2 L), top cut off by the teacher where the shoulders start — 13 (one per pair)
- Wide, straight-sided tubs (ice cream or takeaway containers) — 13
- Rulers with millimetre markings — 13
- Masking tape and a marker — 1 roll each
- Watering cans or jugs with a sprinkler rose, for the teacher’s “rain” — 1–2
- Bucket of water to refill the watering can — 1
- Paper towel — 1 roll
Teacher setup
- Cut the tops off the bottles below the shoulder with sharp scissors or a craft knife (teacher only), and cover the cut edge with masking tape.
- Pour a little water into each bottle until the bumpy base is just covered. Mark this level as 0 on a strip of masking tape; students measure from this line.
- Choose a flat, open spot outside away from trees and roofs, or a tiled area inside.
- Print one investigation record per pair.
Safety and adaptations
- Only the teacher cuts the bottles; tape over cut edges.
- Wipe up spills straight away so no one slips.
- If working outside, wear hats.
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.
- Pairs predict which container will show the deeper water, and why.
- Place the bottle gauge and the tub side by side, touching, on flat ground.
- The teacher makes it “rain” over each pair’s containers by moving the watering can slowly back and forth above both for 20 seconds.
- Measure the depth in each container in millimetres. In the bottle, measure from the 0 line; in the tub, stand the ruler straight up on the bottom.
- Repeat for a second and third trial without emptying, recording the total depth each time.
- Compare: was the depth about the same? Which container held more water?
Teacher modelling prompt
Hold up the bottle and the tub. Think aloud: “I am changing only the width of the container. Both go side by side, so they get the same rain. I will measure the depth from the 0 line with a ruler held straight up, looking at the water at eye level.” Demonstrate reading a depth.
Record and explain evidence
Recording question: Does a wide container catch deeper rain than a narrow one?
| Trial | Narrow bottle: depth (mm) | Wide tub: depth (mm) | About the same depth? | Which held more water? |
|---|---|---|---|---|
| ________________ | ________________ | ________________ | ________________ | ________________ |
Example recording headings; record actual observations, including inconclusive results.
Discussion prompt
Which claim fits our measurements?
Check understanding
What should pupils know? What does a rain gauge measure, and in what unit?
Explain with evidence: Two pairs used different containers in the same rain. One measured 11 mm and one 12 mm. Is this a big difference? Why might it happen?
Apply the idea: Your gauge shows 8 mm on Monday morning. Where did that water come from in the water cycle, and what will happen to it if you leave it in the sun?
Teacher answer guidance and saved classroom work are available through the main lesson experience where supported.