Prep
- ✓ Parts per pair: battery holder, switch, two lamps, enough blue snap wires, and base grid.
- ✓ Use the same battery and two lamps for both comparisons.
- ✓ Choose the reliability brief: two room lights, two exit indicators, or another system where one failure should not shut down both outputs.
Deck map
Day 3: slides 14-18. Leave slide 18 projected.
Day 4: slides 19-23. Leave slide 23 projected.
Day 5: slides 24-27. Leave slide 26 projected; close with slide 27 and the Xello/fallback check-in.
Teacher moves
- Series: identify the one route before students build. Remove one lamp and trace where the route ends.
- Parallel: locate the branch and return points. Remove one lamp and observe the other branch.
- Make students use evidence, not the memorized phrase “parallel is better.” The right circuit depends on the job.
- Reliability challenge: partner traces the route, removes one load, and records whether the other output stays on.
Answers + misconception
Series: one path; remove one lamp and both go out. Parallel: multiple branches; remove one lamp and the other can stay on.
Brightness can change, but brightness does not define series or parallel. Path structure does.
If time is tight
Use physical builds for series and parallel, then complete the reliability challenge as a diagram and prediction. Do not skip the failure test comparison.