Energy | Mini Lesson
In this 15-minute mini lesson, Grade 12 students learn how energy changes during chemical reactions and how to identify exothermic and endothermic processes using simple examples and a quick exit check.
| Term | Definition |
|---|---|
| Energy | The ability to do work or cause change. |
| Exothermic | A reaction that releases energy to the surroundings, usually as heat. |
| Endothermic | A reaction that absorbs energy from the surroundings. |
| Surroundings | Everything outside the chemical system being studied. |
| Thermal energy | Energy related to the motion of particles and experienced as heat. |
Ask students: 'Why does a hand warmer feel hot, and why does an instant cold pack feel cold?' Briefly collect 2-3 responses.
Think and share quick ideas using prior knowledge.
Define energy change in reactions. Introduce exothermic and endothermic with one clear example of each and a simple energy arrow diagram on the board.
Listen, take brief notes, and repeat key terms aloud.
Show two reaction descriptions and ask students to identify whether each is exothermic or endothermic and explain why in one sentence.
Respond individually or with a partner, then share answers.
Give a short exit ticket with 2 items: one multiple-choice question and one short response identifying the energy type of a reaction.
Complete independently and submit before leaving.
Review the main idea: exothermic reactions release energy, endothermic reactions absorb energy. Restate the difference using the examples from class.
Answer one final oral question: 'Which reaction type adds energy to the system?'
Students leave with the essential takeaway that chemical reactions involve energy transfer, and that exothermic reactions release energy while endothermic reactions absorb it.
Formative assessment is the 2-item exit ticket used to check whether students can correctly classify a reaction as exothermic or endothermic and explain their reasoning in simple terms.