Mixing Solids and Liquids

Active learning works for this topic because mixing solids and liquids requires students to observe changes firsthand, which builds concrete understanding of dissolving and suspensions. When students test predictions with real materials, they confront misconceptions through tangible evidence rather than abstract explanations.

• 3rd Year
• Exploring Our World: Scientific Inquiry and Discovery
• 4 activities
• 25 min–50 min

Learning Objectives

1. Classify solids as soluble or insoluble in water based on experimental observation.
2. Compare the properties of a mixture (e.g., sand and water) to the properties of its original components.
3. Explain why different solids exhibit varying degrees of solubility in water.
4. Design a method to separate a suspension of sand and water using common classroom materials.
5. Analyze the visual changes in a liquid when a solid dissolves or forms a suspension.

Stations Rotation

⏱ 45 min·Small Groups

Stations Rotation: Dissolving or Suspending?

Prepare stations with salt, sugar, sand, and chalk powder in water cups. Students predict solubility, stir for one minute, observe settling or clarity over five minutes, and sketch changes. Rotate groups every 10 minutes to test all solids.

Prepare & details

Explain why some solids dissolve in water while others do not.

Facilitation Tip: During Station Rotation: Dissolving or Suspending?, place clear containers of water and solids at each station so students can see changes from multiple angles.

Setup: Tables/desks arranged in 4-6 distinct stations around room

Materials: Station instruction cards, Different materials per station, Rotation timer

• Remember
• Understand
• Apply
• Analyze
• Self-Management
• Relationship Skills

Inquiry Circle

⏱ 30 min·Pairs

Pairs: Prediction Testing

Pairs list five household solids and predict if they dissolve in water. Test two each, stir uniformly, time dissolution, and discuss why some work and others do not. Record in a shared class chart.

Prepare & details

Compare the properties of a mixture to the properties of its original components.

Facilitation Tip: During Prediction Testing, ask pairs to write their predictions before testing to make their reasoning visible.

Setup: Groups at tables with access to source materials

Materials: Source material collection, Inquiry cycle worksheet, Question generation protocol, Findings presentation template

• Analyze
• Evaluate
• Create
• Self-Management
• Self-Awareness

Inquiry Circle

⏱ 50 min·Small Groups

Small Groups: Separation Challenge

Mix sand and salt in water; groups design filters using coffee filters, sieves, or cloth. Test methods, evaporate remaining water to recover salt, and evaluate which separation worked best based on recovery amount.

Prepare & details

Design a method to separate sand from water.

Facilitation Tip: During Separation Challenge, provide filter paper, magnets, and evaporation dishes so students can explore multiple separation methods.

Setup: Groups at tables with access to source materials

Materials: Source material collection, Inquiry cycle worksheet, Question generation protocol, Findings presentation template

• Analyze
• Evaluate
• Create
• Self-Management
• Self-Awareness

Inquiry Circle

⏱ 25 min·Whole Class

Whole Class: Property Demo

Demonstrate mixing flour and water versus sugar and water. Class observes and votes on property changes, then brainstorms real-life examples like cake batter or syrup. Chart comparisons on board.

Prepare & details

Explain why some solids dissolve in water while others do not.

Facilitation Tip: During Property Demo, use a spoon to stir mixtures slowly so students can time how long dissolving takes for different solids.

Setup: Groups at tables with access to source materials

Materials: Source material collection, Inquiry cycle worksheet, Question generation protocol, Findings presentation template

• Analyze
• Evaluate
• Create
• Self-Management
• Self-Awareness

Teaching This Topic

Teach this topic by letting students work with real materials first, then introducing vocabulary and concepts to explain what they observed. Avoid rushing to definitions; instead, let students describe their observations in their own words before formalizing terms like 'solution' or 'suspension.' Research suggests hands-on mixing helps students distinguish dissolving from suspending, which is foundational for later chemistry topics.

What to Expect

Successful learning looks like students accurately predicting whether a solid will dissolve, explaining observations with evidence from their tests, and using vocabulary such as 'solution' or 'suspension' correctly. They should connect their observations to the idea that mixtures retain the properties of their original components.

Watch Out for These Misconceptions

Common Misconception

During Station Rotation: Dissolving or Suspending?, watch for students who assume all solids will dissolve if stirred long enough. Redirect by asking them to observe the sand station closely and describe what happens to the particles over time.

What to Teach Instead

During Station Rotation: Dissolving or Suspending?, have students stir each mixture for the same amount of time, then compare clarity and particle visibility. Ask them to explain why sand particles remain visible while salt disappears.

Common Misconception

During Separation Challenge, watch for students who think mixtures create new substances. Redirect by asking them to separate the mixture back into its original parts using tools like filters or evaporation.

What to Teach Instead

During Separation Challenge, remind students to test if the separated solids match the original, such as tasting recovered salt to confirm it tastes the same as before mixing.

Common Misconception

During Property Demo, watch for students who believe dissolved solids are gone forever. Redirect by asking them to predict what will happen to the water as it evaporates.

What to Teach Instead

During Property Demo, set a small dish of saltwater aside and observe it daily, asking students to record changes and taste the recovered salt when the water is gone.

Assessment Ideas

Quick Check

After Station Rotation: Dissolving or Suspending?, provide three containers with water and different solids (salt, sugar, sand). Ask students to predict which will dissolve, mix them, then explain their observations using full sentences.

Exit Ticket

After Separation Challenge, give students an exit ticket with a drawing of a mixture and ask them to write two sentences explaining how they would separate the components and why their method works.

Discussion Prompt

During Property Demo, ask students: 'Your sugar didn’t dissolve in cold water. What could you change to help it dissolve faster?' Listen for ideas about stirring, heating, or using more water, and note which students connect these actions to particle movement.

Extensions & Scaffolding

• Challenge early finishers to create a mixture that dissolves completely and one that forms a suspension, then explain their choices to a peer.
• Scaffolding for struggling students: Provide magnifying glasses to examine solids before and after mixing, helping them see particles that dissolve versus those that settle.
• Deeper exploration: Ask students to test how temperature affects dissolving by comparing hot, room temperature, and cold water with the same solid.

Key Vocabulary

dissolve	When a solid breaks down into a liquid, becoming evenly mixed and often disappearing from view.
soluble	Describes a solid that can dissolve in a liquid.
insoluble	Describes a solid that cannot dissolve in a liquid and will typically settle or float.
suspension	A mixture where solid particles are dispersed in a liquid but do not dissolve, often settling out over time.
mixture	A substance made by combining two or more different materials that retain their own properties.