Science · Grade 6 · Matter: Properties and Physical Changes · Term 1

Types of Mixtures: Solutions, Suspensions, Colloids

Students explore different types of mixtures and their unique characteristics, including methods of identification.

• Ontario Curriculum Expectations
• MS-PS1-1

About This Topic

Types of mixtures include solutions, suspensions, and colloids, distinguished by particle size and behavior in a solvent. Solutions are homogeneous mixtures where solute particles dissolve completely and stay dispersed, passing through filters unchanged. Suspensions feature larger particles that settle upon standing and can be separated by filtration. Colloids fall in between, with particles small enough to remain suspended but large enough to scatter light, as seen in the Tyndall effect with items like fog or gelatin.

This content aligns with the Ontario Grade 6 Matter: Properties and Physical Changes unit, supporting investigations into physical properties and separation methods. Students compare mixture characteristics, design experiments to identify types, and explain how particle size affects settling, filtration, and clarity, building foundational skills for understanding matter changes.

Active learning excels with this topic through hands-on mixing and testing labs. Students create their own mixtures, observe changes over time, and use simple tools like flashlights and filters. These experiences make particle size concepts visible, encourage peer discussion during classification, and develop experimental design skills essential for scientific inquiry.

Key Questions

1. Compare the characteristics of solutions, suspensions, and colloids.
2. Design an experiment to distinguish between a solution and a suspension.
3. Explain how particle size influences the properties of different mixtures.

Learning Objectives

• Classify common substances as solutions, suspensions, or colloids based on their observable properties.
• Compare the particle behavior and separation methods for solutions, suspensions, and colloids.
• Design an experiment to differentiate between a solution and a suspension using filtration and observation over time.
• Explain how the size of particles in a mixture affects its stability and appearance, referencing the Tyndall effect.
• Analyze the characteristics of a given mixture to determine if it is homogeneous or heterogeneous.

Before You Start

Properties of Solids, Liquids, and Gases

Why: Students need to understand the basic states of matter to comprehend how substances behave when mixed.

Introduction to Matter and Its Changes

Why: This topic builds on the foundational understanding of what matter is and that it can undergo physical changes, such as dissolving.

Key Vocabulary

Solution	A homogeneous mixture where one substance dissolves completely into another, forming a clear, uniform appearance. Solute particles are too small to be seen and do not settle out.
Suspension	A heterogeneous mixture containing solid particles that are sufficiently large to settle out over time or be filtered. The mixture appears cloudy or opaque.
Colloid	A mixture with particles larger than those in a solution but smaller than those in a suspension. These particles remain dispersed and scatter light, but do not settle out easily.
Tyndall Effect	The scattering of a light beam by the large particles in a colloid or suspension, making the beam visible. Solutions do not exhibit this effect.
Homogeneous Mixture	A mixture that has a uniform composition and appearance throughout. Solutions are examples of homogeneous mixtures.
Heterogeneous Mixture	A mixture that does not have a uniform composition. Different parts of the mixture may have different properties. Suspensions and colloids are examples.

Watch Out for These Misconceptions

Common Misconception

All mixtures settle out over time.

What to Teach Instead

Solutions do not settle because particles are molecularly dispersed, unlike suspensions. Hands-on settling observations in jars help students see the difference directly. Group discussions refine ideas as they compare timed data across mixtures.

Common Misconception

Colloids are just another type of solution.

What to Teach Instead

Colloids scatter light due to larger particles, unlike clear solutions. Testing with flashlights during labs reveals the Tyndall effect, correcting this view. Peer teaching in pairs strengthens understanding through shared demonstrations.

Common Misconception

Particle size does not affect filtration.

What to Teach Instead

Larger particles in suspensions get trapped, while solutions pass through. Filtration stations allow students to experiment and witness this firsthand. Collaborative analysis of filter residues clarifies the link between size and separation.

Active Learning Ideas

Lab Stations: Mixture Creation

Prepare stations for salt water (solution), sand water (suspension), and cornstarch water (colloid). Small groups mix ingredients, record initial appearance, then let sit for 10 minutes to check settling. Shine flashlights through each to test Tyndall effect.

45 min·Small Groups

Filtration Challenge: Pairs

Pairs filter samples of a solution, suspension, and colloid using coffee filters and funnels. Note residue on filters and clarity of filtrate. Discuss how particle size predicts results and sketch findings.

30 min·Pairs

Shake and Observe Demo: Whole Class

Demonstrate shaking jars of each mixture type, then observe settling over 20 minutes as a class. Students predict and time settling, then share data on class chart. Extend with student-led predictions for new mixtures.

40 min·Whole Class

Particle Size Sort: Individual

Provide images or samples of particles from fine salt to sand. Individuals sort by estimated size, predict mixture type, then test one prediction by mixing. Compare results in plenary.

25 min·Individual

Real-World Connections

• Pharmacists prepare liquid medications, distinguishing between solutions (like cough syrup) and suspensions (like some antibiotic suspensions) to ensure proper dosage and effectiveness, as particles in suspensions must be shaken to redistribute.
• Food scientists develop products like salad dressings and milk. Emulsifiers are used to create stable colloids from oil and water-based ingredients, preventing separation, while milk itself is a colloid containing fat globules suspended in water.
• Environmental engineers analyze water samples from rivers and lakes, identifying suspensions of silt or pollutants that can be removed through filtration or settling processes to improve water quality.

Assessment Ideas

Exit Ticket

Provide students with three labeled beakers containing water, salt water (solution), muddy water (suspension), and milk (colloid). Ask students to write down one observation for each beaker that helps them classify it as a solution, suspension, or colloid. Include one question: 'Which mixture would you need to shake before using and why?'

Quick Check

Present students with images of various mixtures (e.g., clear juice, orange juice with pulp, fog, sand in water). Ask them to label each image as a solution, suspension, or colloid and provide one reason for their classification, focusing on particle visibility or settling.

Discussion Prompt

Pose the question: 'Imagine you are making a science fair project that requires separating components of a mixture. How would the type of mixture (solution, suspension, or colloid) influence the method you choose for separation?' Facilitate a class discussion comparing filtration, evaporation, and settling.

Frequently Asked Questions

What are the key differences between solutions, suspensions, and colloids?

Solutions are clear, homogeneous mixtures with dissolved particles that do not settle or filter out. Suspensions have visible particles that settle and filter easily. Colloids stay dispersed, scatter light, and may not filter completely. Experiments with everyday materials like salt water, muddy water, and milk help students identify these traits through observation and testing.

How to design an experiment to distinguish solutions from suspensions?

Have students prepare both types, let stand to check settling, then filter. Record clarity, settling time, and filtrate appearance. Variables include particle type; controls ensure fair comparison. This inquiry builds skills in prediction, data collection, and conclusion drawing aligned with Ontario expectations.

How can active learning help students understand types of mixtures?

Active labs like mixing stations and filtration challenges let students manipulate materials, observe settling and light scattering directly, and classify mixtures collaboratively. These reduce reliance on rote memorization, spark questions, and connect particle size to real properties. Structured rotations ensure all participate, deepening retention through hands-on evidence and peer explanation.

Why do particle sizes matter in mixtures grade 6 science?

Particle size determines if a mixture is homogeneous like solutions or heterogeneous like suspensions, affecting properties such as settling, filtration, and light passage. Understanding this explains separation techniques and physical changes. Labs where students predict and test sizes with tools like sieves make the concept concrete and relevant to everyday examples.