Sample lesson fragment (20–30 min) — ready to use

• Topic: Why three points define a plane (geometry)

1. Diagnostic (3 min): individual quick sketch — “Place 3 points. How many planes? Explain.”
2. Peer Instruction (10 min):
   • Individual vote: Do three non-collinear points define a plane? (Yes/No)
   • Pair discussion (4 min): explain reasoning and link to last week’s lesson on lines.
   • Revote and whole-class quick summary. Teacher highlights real-life transfer (stool legs).
3. Transfer task (7 min): in groups of 3, design a simple yard stool. Sketch and explain why 3 legs avoid rocking. Quick gallery walk.
4. Reflection (2–3 min): one-sentence self-check: “I can explain this because ___.”

Quick checklist for class prep

• Is the activity anchored to prior knowledge? ✔
• Is the task challenging but accessible? ✔
• Are roles and deliverables clear? ✔
• Have you trained students in feedback & explanations? ✔
• Will you collect a short individual reflection? ✔
• Do you have a plan for groups that need extra support? ✔