All lessons › Rocks, minerals and soils › Lesson 3
Australian primary science · Year 3 · Lesson 3 of 3
Soil soak test
Inquiry question: Which soil lets water through the fastest?
Check practical materials
Fair testing
What students learn
Soils have different properties. Sand has big grains with big gaps, so water drains through fast. Clay has tiny bits that pack tightly, so water drains slowly. Garden soil is in between.
Success criteria
- I can say what we changed and what we kept the same.
- I can measure how much water drained through.
- I can choose the best soil for a garden and explain why.
Preparation and materials
Before this lesson: Students know soil is made of tiny bits of rock and bits of dead plants (lesson 1).
- Sand from the sandpit — About 1 cup per pair
- Soil from the school garden — About 1 cup per pair
- Sticky clay soil (from a bare patch or dug from under the topsoil), if you can find it — Optional, about 1 cup per pair
- Plastic cups, all the same size — 52 (4 per pair), or 78 with clay soil
- Paper towel — 39 pieces
- Water, plus one cup per pair with a fill line marked — 13 fill-line cups
- Rulers — 13
- Spoons — 13
- Timer (iPad or class clock) — 1 per pair or the class clock
Teacher setup
- Collect sand and garden soil the day before (and clay soil if you can). Pick out sticks, glass and anything sharp. Soil should be slightly damp, not muddy or bone dry.
- Poke 5 small holes in the bottom of half the cups with a skewer (teacher job).
- Mark a fill line about 100 mL up one cup per pair, so every pour is the same amount.
- Print one investigation record per pair.
Safety and adaptations
- Wash hands with soap after touching soil.
- Keep soil away from mouths and eyes. Cover any cuts.
- Use soil from the school yard, not bagged potting mix: potting mix can carry germs that cause lung infections.
- Only the teacher pokes holes in cups.
- Wipe up spills so no one 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.
- Feel each soil. Is it gritty, smooth or sticky?
- Predict which soil will let the most water through.
- Line each holey cup with paper towel, add 4 spoons of soil and sit it on an empty cup.
- Pour in water from the fill-line cup and start the timer.
- After 1 minute, lift the top cup and measure the depth of water in the bottom cup in mm.
- Repeat for each soil, then compare the results with your prediction.
Teacher modelling prompt
Show one set-up: a cup with holes, lined with paper towel, sitting on an empty cup. Think aloud: “I am changing only the soil. Same cups, same 4 spoons of soil, same amount of water, same time: 1 minute. Then I lift the top cup and measure how deep the water is in the bottom cup.”
Record and explain evidence
Recording question: Which soil lets water through the fastest?
| Soil | What it feels like | Our prediction (1 = most water) | Water after 1 minute (mm) |
|---|---|---|---|
| ________________ | ________________ | ________________ | ________________ |
Example recording headings; record actual observations, including inconclusive results.
Discussion prompt
Whose choice is better for growing vegetables? Use our results.
Check understanding
What should pupils know? Why does water go through sand quickly?
Explain with evidence: What did we keep the same in our test? Why?
Apply the idea: A school wants a sports field that dries quickly after rain. Should the soil underneath be sandy or full of clay? Why?
Teacher answer guidance and saved classroom work are available through the main lesson experience where supported.