Electricity | Substitute Teacher
Students review how electricity is produced and used in chemical systems, focusing on redox reactions, electron flow, and the connection between chemical change and electrical energy. This 20-minute lesson is structured for a substitute teacher and emphasizes discussion, guided practice, and quick checks for understanding.
| Term | Definition |
|---|---|
| Oxidation | Loss of electrons; occurs at the anode in a galvanic cell. |
| Reduction | Gain of electrons; occurs at the cathode in a galvanic cell. |
| Anode | Electrode where oxidation occurs. |
| Cathode | Electrode where reduction occurs. |
| Galvanic cell | A device that converts chemical energy into electrical energy through a spontaneous redox reaction. |
| Electron flow | Movement of electrons through an external circuit from anode to cathode. |
Display: 'What must happen to electrons for a battery to produce electricity?' Ask students to write one sentence and be ready to share.
Write a brief response, then share ideas with the class.
Review the core idea: redox reactions transfer electrons, and that transfer can be harnessed as electrical energy. Define oxidation, reduction, anode, and cathode. Emphasize the memory aid OIL RIG and that electrons move from anode to cathode in a galvanic cell.
Listen, annotate notes, and answer quick oral questions.
Show a simple voltaic cell diagram or reaction, such as Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s). Ask: What is oxidized? What is reduced? Which electrode is the anode? Which is the cathode? Where do electrons travel?
Work individually for 1 minute, then discuss answers with a partner and volunteer responses.
Present a second prompt: 'If the metal at the anode changes to ions, what happens to its mass? Why?' or 'How would reversing a redox reaction affect electricity production?' Guide students to connect particle-level thinking to observable changes.
Respond in complete sentences and explain reasoning using vocabulary.
Summarize: electricity in a galvanic cell comes from spontaneous electron transfer in a redox reaction. Have students state one thing they now know about anode/cathode or oxidation/reduction.
Share a final takeaway or write one exit-style sentence orally if time is short.
End by reinforcing the big idea: a battery works because a redox reaction separates electron transfer into a circuit, creating usable electricity. Students should leave able to identify oxidation, reduction, anode, cathode, and electron flow in a simple cell.