All lessons › Fire, fuel and change › Lesson 1
Australian primary science · Year 6 · Lesson 1 of 3
Burning is a one-way change
Inquiry question: What makes burning different from melting?
Marked no materials needed
Classifying
What students learn
Reversible changes, like melting, can be undone and make no new substance. Burning is an irreversible change: it needs fuel, heat and oxygen, and turns the fuel into new substances such as ash, smoke, carbon dioxide and water vapour.
Success criteria
- I can sort changes into reversible and irreversible.
- I can give evidence that a new substance has formed.
- I can name the three sides of the fire triangle.
Preparation and materials
Before this lesson: Students know that melting and freezing are changes of state.
- iPads with Bottlebrush Education open (nothing else needed) — 13 (one per pair)
- Projector or big screen — 1
Teacher setup
- Open Materials & chemistry › Lab › Change sorter on your screen to demonstrate.
- Check the iPads are charged.
Safety and adaptations
Follow school science and equipment risk assessment procedures for the materials used.
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 play Change sorter and record each change with their evidence.
- Open Melt-o-meter: heat chocolate or butter to 70°C, then to 180°C. Record what happens each time.
- Decide which results are reversible and which are irreversible, and why.
- Draw the fire triangle and label it with the candle: what is the fuel, the heat and the oxygen?
- Explain where the candle wax goes when it burns.
Teacher modelling prompt
On the big screen, open Change sorter and think aloud on the Toasting bread card when it comes up (the cards are shuffled): “Toasting bread. The brown part tastes and smells different, and cooling won’t turn it back into soft bread. A new substance formed, so it’s irreversible.” Then draw the fire triangle on the board: fuel, heat, oxygen.
Record and explain evidence
Recording question: What makes burning different from melting?
| Change | Reversible or irreversible? | Evidence (new substance? can it be undone?) | Is it burning? (yes or no) |
|---|---|---|---|
| ________________ | ________________ | ________________ | ________________ |
Example recording headings; record actual observations, including inconclusive results.
Discussion prompt
Which explains why the candle gets smaller even with no drips?
Check understanding
What should pupils know? What is the difference between a reversible and an irreversible change? Give one example of each.
Explain with evidence: Is burning toast reversible or irreversible? Give two pieces of evidence.
Apply the idea: A firefighter puts a blanket over a small pan fire. Which side of the fire triangle does this remove? Explain.
Teacher answer guidance and saved classroom work are available through the main lesson experience where supported.