Lesson Plan

• Describe how particle spacing and intermolecular forces affect thermal conduction in gases and liquids.
• Explain why collisions are less frequent in gases and most liquids compared with solids.
• Compare typical thermal conductivity values of solids, liquids, and gases using particle‑level reasoning.
• Apply the concept to everyday insulation examples such as thermos flasks and foam.

• Projector and screen
• Whiteboard and markers
• Printed handout with particle‑spacing diagram
• Worksheet with comparison table
• Sample materials (metal rod, water container, thermometer)
• Laptop for short simulation video

Imagine a metal spoon heating up quickly in a pot while a plastic spoon stays cool. Students already know heat flows from hot to cold and have seen the macroscopic form of Fourier’s law. By the end of the lesson they will be able to explain at particle level why gases and most liquids conduct heat poorly.

1. Do‑now (5') – Quick question: “Why does a thermos keep drinks hot?” Students write brief answers.
2. Mini‑lecture with diagram (10') – Show particle spacing in solids, liquids, gases and discuss collision frequency.
3. Guided inquiry (15') – Examine the conductivity table; students discuss in pairs why liquids and gases have lower k values.
4. Demonstration (10') – Heat a metal rod and a water‑filled container; students feel the difference in heat transfer.
5. Worksheet activity (10') – Write a concise particle‑level explanation for poor conduction in gases and liquids.
6. Check for understanding (5') – Exit ticket: one sentence stating the main reason gases conduct heat poorly.

We recap that wide particle spacing, weak intermolecular forces, and random high‑speed motion limit collisions and thus heat flow in gases and most liquids. Students hand in their exit tickets and the teacher highlights common misconceptions. For homework, learners research another insulating material (e.g., aerogel) and explain its effectiveness using the particle concepts discussed.