All lessons › Challenge: Particle puzzles › Lesson 2
Australian primary science · Years 5–6 (challenge) · Lesson 2 of 3
Element, compound or mixture?
Inquiry question: How can particle pictures tell us whether something is an element, a compound or a mixture, and how do we separate a mixture?
Marked no materials needed
Classifying
What students learn
Elements contain one kind of atom. Compounds have two or more kinds of atoms joined together. Mixtures have different substances mingled but not joined, so their properties let us separate them.
Success criteria
- I can sort particle pictures into elements, compounds and mixtures.
- I can choose a separation method and give the property it relies on.
- I can put separation steps in a sensible order and explain why the order matters.
Preparation and materials
Before this lesson: Students know that dissolving makes a mixture and that some mixtures can be separated (Change detectives).
- iPads with Bottlebrush Education open (nothing else needed) — 13 (one per pair)
- Projector or big screen — 1
Teacher setup
- Open Materials & chemistry › Lab › Element, mixture or compound? on your screen to demonstrate.
- Check the iPads are charged and set to Your year › Years 5–6.
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 open Element, mixture or compound? and compare all three models.
- Open Molecule builder and build water, oxygen gas and carbon dioxide. Record each as element or compound.
- Sort the six substances in the source sheet into element, compound or mixture, giving a reason for each.
- Be the engineer: open Separation station and test all four mixtures to find which tool works for each and why.
- Plan how to separate the ‘beach sample’ in the source sheet into sand, iron, salt and water. Number the steps and give the property each step uses.
Teacher modelling prompt
Open Element, mixture or compound? on the big screen and show all three models. Think aloud: “In the element, every particle is made of the same atom. In the compound, each particle has two kinds of atom stuck together. In the mixture, there are two different kinds of particle sharing the space, but they aren’t joined.” Then open Molecule builder and build H₂O: “This is a compound, so I can’t pull the hydrogen out with a filter.”
Record and explain evidence
Recording question: Is it an element, a compound or a mixture, and how could we separate the mixtures?
| Substance | Element, compound or mixture? | Reason (particle picture) | If a mixture: separation step | Property used |
|---|---|---|---|---|
| ________________ | ________________ | ________________ | ________________ | ________________ |
Example recording headings; record actual observations, including inconclusive results.
Discussion prompt
Use what you saw in Separation station to decide which plan works.
Check understanding
What should pupils know? Explain the difference between a compound and a mixture, using a particle picture.
Explain with evidence: Why can’t you separate water into hydrogen and oxygen with a filter or a magnet?
Apply the idea: Salt farms at the edge of the sea let seawater sit in shallow ponds in the sun. Explain how this separates the salt.
Teacher answer guidance and saved classroom work are available through the main lesson experience where supported.