All lessons › Kitchen science: squish, bubble and freeze › Lesson 2
Australian primary science · Years 3–4 · Lesson 2 of 4
Best bubble mixture
Inquiry question: Which bubble mixture makes the biggest bubbles?
Check practical materials
Fair testing
What students learn
A fair test changes only one thing, measures the result the same way each time and keeps everything else the same.
Success criteria
- I can name the one thing we changed and the things we kept the same.
- I can measure bubble rings with a ruler.
- I can use my results to choose the best mixture.
Preparation and materials
Before this lesson: Students know that materials have properties we can test.
- Dishwashing liquid — 1 bottle
- Water — 1 jug per table
- Plastic cups — 39 (3 per pair)
- Straws — 26 (one per student)
- Teaspoons — 13
- Trays or plastic plates — 13
- Rulers — 13
- Sugar or glycerine (optional extra test) — 1 small bag or bottle
Teacher setup
- Label cups 1, 2 and 3 for each pair.
- Wet each tray lightly before students start.
Safety and adaptations
- Blow out through the straw, never suck in.
- One straw per student; no sharing.
- Wipe up spills; soapy floors are slippery.
- Detergent stings eyes: wash hands afterwards.
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.
- Put 1/2 cup of water in each cup.
- Add 1 spoon of dishwashing liquid to cup 1, 2 spoons to cup 2 and 3 spoons to cup 3. Stir gently.
- Dip a straw in cup 1 and blow one dome bubble on the wet tray. Measure the ring across.
- Repeat with cups 2 and 3, blowing the same way.
- Do each mixture twice. Record both measurements.
- Which mixture made the biggest bubbles?
Teacher modelling prompt
Wet a tray. Dip a straw in plain water and blow gently onto the tray. The bubble pops at once. Say: “That’s how to blow a dome bubble and measure the wet ring. Now it’s your job to find which mixture works best.” Show how to measure the ring across its widest part.
Record and explain evidence
Recording question: Which bubble mixture makes the biggest bubbles?
| Mixture | Bubble ring try 1 (cm) | Bubble ring try 2 (cm) | What I noticed |
|---|---|---|---|
| ________________ | ________________ | ________________ | ________________ |
Example recording headings; record actual observations, including inconclusive results.
Discussion prompt
Which claim matches our measurements, and how could we make the test fairer?
Check understanding
What should pupils know? Why don’t bubbles form with plain water?
Explain with evidence: Leo blew hard for cup 3 and softly for cup 1. Why isn’t that fair?
Apply the idea: You want bubbles that last longer. What one thing would you change and test?
Teacher answer guidance and saved classroom work are available through the main lesson experience where supported.