Understanding Types of Matter

Curriculum Alignment

Australian Curriculum: Science – Year 8

• Science Understanding – Chemical Sciences
  ACSSU225: Particles make up all substances and the particle model can be used to explain the properties of solids, liquids and gases.
  ACSSU226: Chemical change involves substances reacting to form new substances.
  ACSSU187: Different types of physical changes can be used to separate mixtures.

• Science Inquiry Skills
  ACSIS148, ACSIS149, ACSIS150, ACSIS151: Plan, conduct and evaluate scientific investigations, including identifying variables and analysing data.
  ACSIS145, ACSIS146: Communicate scientific ideas using appropriate terminology and representations.

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Lesson Length

Duration: 40 minutes
Class Size: 25 students
Setting: Science classroom/lab

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Learning Objectives

By the end of this lesson, Year 8 students will be able to:

1. Define and recall terms: matter, element, compound, mixture, pure, and impure.
2. Classify substances as element, compound, homogeneous (solution) or heterogeneous (suspension).
3. Explain the concepts of solute, solvent, solubility, and examples of soluble and insoluble substances.
4. Conduct a guided experiment to test the solubility of various solids in water and oil.
5. Understand and communicate the role of water and oils as solvents.
6. 🏋️Extension: Define a colloid and identify real-life colloids.
7. 🧪🏋️Extension Investigation: Observe mixture behaviour and categorise as solution, suspension or colloid.

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Required Materials

Each group (5 groups total):

• Beakers
• Stirring rods
• Water
• Vegetable oil
• Table salt
• Sugar
• Sand
• Flour
• Milk
• Iodine solution
• Iron filings (optional)
• Filter paper
• Worksheets
• Safety glasses

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Lesson Breakdown

⏰ 0:00 – 0:05 | Introduction & Recap

Teacher-Led Discussion

• Define matter: anything that has mass and takes up space.
• Recall: elements (e.g. oxygen), compounds (e.g. H₂O), and mixtures (e.g. air, salad).
• Ask: “Is saltwater a compound or a mixture? Why?”
• Use a whiteboard diagram to compare atomic/molecular structures of an element, compound, and mixture.

Visual Aid: Show atomic structure diagram – elements (single type of atom), compounds (bonded atoms), mixtures (different particles not chemically bonded).

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⏰ 0:05 – 0:15 | Concept Development

Definitions + Matching Activity

Provide students with flashcards to match the following terms to their definitions and examples (done in table groups):

Term	Definition	Example
Mixture	Two or more substances not chemically bonded	Air, salad
Pure	Made of only one type of particle	Gold, distilled water
Impure	Contains more than one type of particle	Tap water, soil
Soluble	Can dissolve in a solvent	Sugar in water
Insoluble	Cannot dissolve in a solvent	Sand in oil
Solute	The substance that dissolves	Salt
Solvent	The substance doing the dissolving	Water
Solution	A homogeneous mixture where the solute is dissolved	Saltwater
Suspension	A heterogeneous mixture where particles settle over time	Sand in water
Homogeneous	Uniform appearance and composition	Coffee
Heterogeneous	Non-uniform, visibly distinguishable parts	Fruit salad

Rotate tables to check each other’s work for peer assessment.

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⏰ 0:15 – 0:30 | Experiment Activity

🧪Guided Practical: Solubility Testing

Students work in 5 groups with labelled trays and follow a worksheet:

Task: Test the solubility of sugar, salt, sand, and flour in water and oil.

1. Add 100ml of water to one beaker and 100ml of oil to another.
2. Add 1 teaspoon of each substance to each liquid.
3. Stir, observe, and record:
   • Does it dissolve?
   • Is the mixture homogeneous or heterogeneous?
   • Does it form a suspension or solution?
4. Optional: Use filter paper to separate undissolved solids and analyse.

Record Observations:

• Salt: Soluble in water (solution), insoluble in oil.
• Sugar: Soluble in water, partially in oil.
• Sand: Insoluble in both (forms suspension).
• Flour: Colloid-like in water; difficult to filter.

Safety Check: All students wear safety glasses. No food substances to be consumed.

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⏰ 0:30 – 0:35 | Reflection & Water as a Solvent

Mini Discussion:

• “Why do you think water is called the ‘universal solvent’?”
• Highlight that water dissolves many substances due to its polarity.
• Extension Thinking: Oils don’t mix with water—do they behave as solvents? Yes—non-polar solvents dissolve non-polar substances.

Tying Back to Real-Life:

• Cosmetics (oil-based lotions)
• Cooking (olive oil dissolves flavour compounds)
• Cleaning (soapy vs oily surfaces)

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⏰ 0:35 – 0:40 | Extension Challenge + Exit Ticket

🏋️‍ Extension: What is a Colloid?

Introduce the term colloid: a mixture where particles do not settle and cannot be filtered easily (e.g. milk, fog, mayonnaise).

🧪Mini Investigation (optional for fast-finishers):

• Mix small amounts of milk and iodine, or flour and water.
• Observe: Does it form a suspension or colloid?

✅ Quick Exit Ticket (collected at the door): Students answer:

1. Define solution & give one example.
2. What is one insoluble substance tested today?
3. What is a colloid?

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Teacher Tips

👩‍🏫 Differentiation:

• Pair EAL/D students with strong readers.
• Provide visuals and sentence starters for scientific definitions.

🎓 Higher Order Questioning:

• Why is solubility important in medicine?
• Can a substance behave as both solute and solvent?

🌱 Sustainability Link:

• What happens when insoluble substances pollute water sources?

📘 Cross-Curricular Opportunity:

• English: vocab development using scientific terminology.
• Geography: water systems—where soluble substances end up.

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Assessment Opportunities

• Formative: Participation in group sorting, verbal contributions.
• Practical: Solubility experiment observations and accuracy.
• Exit Ticket: Evidence of understanding key terms and classification.

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Homework / Extension Suggestion

Ask students to find 3 items in their home (e.g. toothpaste, juice, gelatine) and classify them as solution, suspension, or colloid. Bring to next class for show-and-tell/scientific breakdown.

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Conclusion

This engaging, hands-on lesson introduces Year 8 students to the foundational chemical science concepts of matter, mixtures, and solubility, aligning perfectly with the Australian Curriculum. It offers opportunities for inquiry, teamwork, and real-world connections while preparing students for more complex chemistry in senior years.