Science · Grade 7

Active learning ideas

Physical and Chemical Changes

Active learning works because physical and chemical changes are best understood through direct observation and hands-on testing. Students need to see, touch, and test transformations themselves to build lasting understanding. These activities provide structured ways for students to interact with evidence and apply criteria in real time.

• Ontario Curriculum Expectations
• MS-PS1-2

• 20–45 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Stations Rotation
• 45 min · Small Groups

Stations Rotation: Change Evidence Stations

Prepare four stations with materials: melting ice (physical), vinegar and baking soda (chemical gas), iodine and starch (color change chemical), and tearing paper (physical). Groups rotate every 10 minutes, observe changes, note evidence, and classify. Debrief as a class to compare results.

Explain how to determine if a chemical change has occurred.

Facilitation Tip

During Change Evidence Stations, circulate and ask each pair to explain which piece of evidence convinced them most, pressing for specificity like ‘the gas bubbles formed new substances.’

What to look for

Present students with a list of 10 transformations (e.g., burning wood, dissolving sugar in water, smashing a rock, baking a cake). Ask them to categorize each as 'Physical' or 'Chemical' and provide one piece of evidence for their choice.

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

Activity 02

• Experiential Learning
• 30 min · Pairs

Pairs Demo: Everyday Tests

Pairs select from options like mixing oil and water, crushing Alka-Seltzer in water, or bending a paperclip. They predict change type, perform test, record observations using a checklist for evidence. Pairs share one finding with the class.

Compare the evidence for a physical change versus a chemical change.

Facilitation Tip

In Everyday Tests, pause between demonstrations to ask students to predict what will happen next, building anticipation and reasoning before revealing outcomes.

What to look for

On an index card, have students describe one experiment they could conduct safely in the classroom to demonstrate a chemical change. They should list the materials and the observable evidence they would look for.

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Activity 03

• Experiential Learning
• 25 min · Whole Class

Whole Class: Classification Challenge

Display 12 images or videos of changes (e.g., cooking egg, sawing wood). Class votes on physical or chemical via hand signals or digital poll, then discusses evidence. Teacher reveals correct classifications with explanations.

Analyze everyday examples to classify them as physical or chemical changes.

Facilitation Tip

For the Classification Challenge, allow students to draft their categories privately first, then discuss as a class to surface misconceptions before finalizing answers.

What to look for

Pose the question: 'If you observe a color change, does it automatically mean a chemical change has occurred?' Facilitate a class discussion where students use examples of both physical and chemical changes to support their arguments.

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Activity 04

• Experiential Learning
• 20 min · Individual

Individual Log: Home Connection

Students list five household changes observed at home, classify each with evidence, and draw before/after sketches. Collect logs next class for group review and correction.

Explain how to determine if a chemical change has occurred.

What to look for

Present students with a list of 10 transformations (e.g., burning wood, dissolving sugar in water, smashing a rock, baking a cake). Ask them to categorize each as 'Physical' or 'Chemical' and provide one piece of evidence for their choice.

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

A few notes on teaching this unit

Teachers should emphasize evidence over memorization, using everyday examples students already know. Avoid rushing to the definitions; instead, let students struggle with classification first, then refine their thinking through discussion. Research shows that having students articulate their reasoning aloud, especially when wrong, strengthens long-term understanding more than immediate correction.

Students will confidently distinguish physical from chemical changes by citing observable evidence. They will use terms like precipitate, reversible, and new substance correctly in context. Classroom discussions will show students grounding their claims in the evidence they collected during activities.

---

Watch Out for These Misconceptions

• During Station Rotation: Change Evidence Stations, watch for students labeling dissolving salt as a chemical change because the substance disappears.

  Direct students to evaporate the dissolved salt on an evaporating dish to recover crystals, reinforcing that the salt’s identity remains intact and the change is physical.

• During Pairs Demo: Everyday Tests, watch for students assuming any color change signals a chemical reaction.

  Have students compare adding food coloring to water versus adding indicator to acid; ask them to describe how the causes and results differ using their observations.

• During Whole Class: Classification Challenge, watch for students classifying crumpled paper or broken glass as chemical changes because they cannot be easily reversed.

  Prompt students to test reversibility by attempting to restore the original shape or form, then discuss whether new substances formed during the process.

---

Methods used in this brief

• Stations Rotation
• Experiential Learning