Science · Grade 10

Active learning ideas

Introduction to Chemical Reactions

Active learning builds lasting understanding in this topic because students must observe and classify tangible evidence to separate chemical changes from physical ones. When students handle materials directly, they connect abstract symbols like 'reactants' and 'products' to real-world phenomena they can see, smell, and feel. This hands-on engagement addresses common misconceptions early by letting students test ideas for themselves before forming conclusions.

• Ontario Curriculum Expectations
• HS-PS1-2

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

Activity 01

• Stations Rotation
• 45 min · Small Groups

Stations Rotation: Reaction Signs

Prepare five stations with safe demos: baking soda and vinegar for gas, steel wool in vinegar for heat, iodine and starch for color change, lead nitrate and potassium iodide for precipitate, and ice melting for physical change. Groups rotate every 7 minutes, predict physical or chemical, observe signs, and record evidence in notebooks.

Differentiate between physical and chemical changes using observable evidence.

Facilitation Tip

During Individual Observation, give students a two-column chart labeled 'Physical' and 'Chemical' so they practice sorting changes systematically rather than relying on memory.

What to look for

Provide students with a scenario, such as 'Wood burning in a fireplace' or 'Ice melting into water.' Ask them to write one sentence explaining whether it is a physical or chemical change and list one piece of evidence supporting their claim.

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

Activity 02

• Experiential Learning
• 30 min · Pairs

Pairs Lab: Energy Changes

Pairs test endothermic (ammonium nitrate in water) and exothermic (calcium chloride in water) reactions using thermometers. They measure initial and final temperatures, graph changes, and classify each reaction. Follow with a class share-out to compare results.

Explain the role of reactants and products in a chemical reaction.

What to look for

Present students with a list of common observations (e.g., 'A gas bubbles form,' 'The solid dissolves,' 'The solution gets warmer'). Ask them to categorize each observation as evidence of a physical change, a chemical change, or potentially either.

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

Activity 03

• Experiential Learning
• 20 min · Whole Class

Whole Class Demo: Reactants to Products

Project a large-scale reaction like elephant toothpaste. Students note reactants (hydrogen peroxide, yeast, dish soap), predict products, and observe foam formation. Discuss atomic rearrangement using molecular models afterward.

Analyze how energy changes indicate whether a reaction is endothermic or exothermic.

What to look for

Pose the question: 'Imagine you mix two clear liquids and a solid forms at the bottom. What are the reactants and the product in this scenario? How do you know a chemical reaction occurred?' Facilitate a brief class discussion to solidify understanding of reactants, products, and evidence.

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

Activity 04

• Experiential Learning
• 25 min · Individual

Individual Observation: Everyday Changes

Students list 10 household changes, classify as physical or chemical with justification, then verify two via simple tests like evaporating saltwater. Submit annotated lists for feedback.

Differentiate between physical and chemical changes using observable evidence.

What to look for

Provide students with a scenario, such as 'Wood burning in a fireplace' or 'Ice melting into water.' Ask them to write one sentence explaining whether it is a physical or chemical change and list one piece of evidence supporting their claim.

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

A few notes on teaching this unit

Experienced teachers approach this topic by front-loading observation skills before introducing definitions, because students learn best when they first experience the phenomenon. Avoid starting with a lecture on reaction types; instead, let students grapple with evidence first and then formalize their findings. Research shows that students retain concepts better when they must justify their classifications using multiple signs, so emphasize collaborative data collection and peer discussion over worksheets.

By the end of these activities, students should confidently identify chemical reactions using multiple signs of change, explain the difference between reactants and products, and classify energy changes as endothermic or exothermic. They will use clear, evidence-based language to justify their reasoning and work collaboratively to compare observations. Success looks like students correcting each other’s claims using data rather than relying on assumptions.

---

Watch Out for These Misconceptions

• During the Individual Observation activity, watch for students assuming that dissolving a solid always signals a chemical change.

  Provide salt, sugar, and baking soda for students to dissolve, then have them evaporate the solutions to recover the original solids. Ask them to taste the residue to confirm no new substance formed, and have them revise their initial claims in their lab notebooks.

• During the Pairs Lab activity, watch for students generalizing that all chemical reactions release heat.

  Ask groups to compare their temperature data and highlight that some reactions caused cooling. Have them identify the endothermic pair and explain to the class why that one absorbed heat, using their data as evidence.

• During the Station Rotation activity, watch for students relying on a single sign, like color change, to confirm a chemical reaction.

---

Methods used in this brief

• Stations Rotation
• Experiential Learning