All lessons › Chemistry detectives › Lesson 3
Australian primary science · Years 5–6 · enrichment · Lesson 3 of 3
Elements, Compounds and Mixtures
Inquiry question: Can a particle model explain what a material contains?
Marked no materials needed
Classification and modelling
What students learn
Classify particle models using evidence about atom types, substances and bonding.
Success criteria
- I can distinguish atom count from atom type.
- I can justify element, compound or mixture.
- I can explain what a model leaves out.
Preparation and materials
Before this lesson: Symbols label atom types. Atoms can join.
- Charged iPad per student or pair — 13 (one per pair)
- Projector / teacher screen — 1
Teacher setup
- Allow 55 minutes: Start 5, Investigate 25, Explain 15, Apply and hand in 10.
- Open the assigned QR and slides. No physical chemicals, samples or printed sheets are needed.
- Use supplied evidence if research sites are blocked. Books use the same questions and headings.
Safety and adaptations
- On-screen inquiry only. Do not collect, taste or mix substances, open batteries or try reactions seen online.
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.
- Read the key and compare Samples A–D.
- Count atom kinds and particle kinds. Classify each sample with reasons.
- Use the classification tool on another example; record a feature supporting your rule.
- Challenge 'all gases are elements' using O₂ and CO₂.
- Describe a compound and a mixture using H and O. Explain the difference and one model limitation.
Teacher modelling prompt
Explain the key: each letter is an element type, a join means bonded. Count types in helium without classifying the mystery samples. Not every compound consists of separate molecules: salt forms a repeating ionic structure.
Record and explain evidence
Recording question: What evidence distinguishes element, compound and mixture?
| Sample | Atom kinds / particle kinds | Classification and reason |
|---|---|---|
| ________________ | ________________ | ________________ |
Example recording headings; record actual observations, including inconclusive results.
Discussion prompt
Use two samples to test these claims.
Check understanding
What should pupils know? Why is O₂ an element but H₂O a compound?
Explain with evidence: Classify D and cite two model features.
Apply the idea: Only CO₂ particles are present. Evaluate: 'It is a mixture because it has two kinds of atoms'.
Teacher answer guidance and saved classroom work are available through the main lesson experience where supported.