Science · 8th Grade

Active learning ideas

Exothermic and Endothermic Reactions

Teaching exothermic and endothermic reactions requires students to move beyond memorization and engage with energy transfer as a tangible process. Active investigations let students feel temperature changes firsthand, turning abstract energy concepts into concrete experiences that stick.

• Common Core State Standards
• MS-PS1-6

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

Activity 01

• Inquiry Circle
• 45 min · Small Groups

Inquiry Circle: Hot or Cold?

Groups use temperature probes or thermometers to measure the temperature change in four reactions: baking soda plus citric acid, calcium chloride plus water, Alka-Seltzer in water, and activated hand warmer contents. Students classify each as exothermic or endothermic and create a bar graph showing temperature change direction and magnitude.

Differentiate between exothermic and endothermic reactions based on energy changes.

Facilitation Tip

During Collaborative Investigation: Hot or Cold?, circulate with an infrared thermometer to confirm temperature changes in real time and prevent false readings from hand placement.

What to look for

Provide students with a list of common chemical processes (e.g., burning wood, melting ice, photosynthesis, a hand warmer activating). Ask them to label each as exothermic or endothermic and briefly justify their choice by stating if energy is released or absorbed.

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

Activity 02

• Stations Rotation
• 35 min · Small Groups

Stations Rotation: Energy Diagrams

Students rotate through stations each showing a reaction scenario with an incomplete energy diagram. They draw the energy profile, label the activation energy, and decide whether the reaction is exothermic or endothermic based on whether the products are lower or higher in energy than the reactants.

Analyze how energy is absorbed or released during various chemical processes.

Facilitation Tip

When running Station Rotation: Energy Diagrams, assign specific roles (reader, sketcher, reporter) to ensure every student contributes to the energy diagram analysis.

What to look for

Ask students to draw two simple diagrams. One diagram should represent an exothermic reaction showing energy leaving the system, and the other should represent an endothermic reaction showing energy entering the system. They should label the energy flow and the resulting temperature change in the surroundings.

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

Activity 03

• Think-Pair-Share
• 20 min · Pairs

Think-Pair-Share: Hand Warmer vs. Cold Pack

Students hold an activated hand warmer and a cold pack simultaneously. They discuss with a partner what is happening at the particle level in each one and write a claim-evidence-reasoning paragraph connecting their sensory observation to energy transfer before sharing with the class.

Predict the temperature change in a system undergoing a specific chemical reaction.

Facilitation Tip

For Think-Pair-Share: Hand Warmer vs. Cold Pack, provide actual samples so students can connect the abstract labels (exothermic/endothermic) to real-world devices they’ve used.

What to look for

Pose the question: 'Imagine you are designing a self-heating meal package for hikers. Would you want the primary reaction inside to be exothermic or endothermic? Explain your reasoning, referencing energy transfer and temperature change.'

• Understand
• Apply
• Analyze
• Self-Awareness
• Relationship Skills

A few notes on teaching this unit

Teachers should emphasize energy flow over labels. Start with phenomena students recognize, like hand warmers heating up, then use bond energy calculations to show energy is transferred through breaking and forming bonds. Avoid explaining reactions as inherently producing or consuming heat without tracing the energy source or sink.

Students will confidently classify reactions by energy flow and predict temperature changes using bond energy principles. They will explain energy transfer in both familiar and unfamiliar examples, showing clear understanding of energy conservation.

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Watch Out for These Misconceptions

• Students think exothermic reactions produce heat from nothing and endothermic reactions lose energy permanently.

  During Collaborative Investigation: Hot or Cold?, ask students to use the bond energy accounting framework provided in their lab sheets to trace energy transfer. In the closing discussion, have groups share where energy comes from in an exothermic reaction and where it goes in an endothermic one.

• Students believe endothermic reactions are incomplete or less significant because they don't produce heat.

  During Station Rotation: Energy Diagrams, include photosynthesis as one of the stations. Ask students to compare the energy flow in photosynthesis to other reactions, emphasizing its global importance and the fact that it is a complete chemical reaction.

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Methods used in this brief

• Inquiry Circle
• Stations Rotation
• Think-Pair-Share