Lesson Plan

• State Ohm’s law and rewrite it as V = IR and I = V⁄R.
• Explain how resistance depends on resistivity, length and cross‑sectional area (R = ρL⁄A).
• Calculate the resistance of a uniform conductor using given dimensions and resistivity values.
• Compare resistivity values of common materials and predict their relative conductivities.
• Describe the effect of temperature on resistivity for conductors and semiconductors.

• Projector and screen
• Whiteboard and markers
• Worksheet with practice problems
• Scientific calculators
• Copper wire sample, ruler, and ammeter (optional demo)
• Handout of resistivity table for common materials
• Diagram of a cylindrical conductor (printed or digital)

Begin with a quick demonstration of a flashlight turning brighter as the battery voltage increases, asking students what governs that change. Review that they already know voltage, current and resistance from previous lessons. Explain that by the end of the lesson they will be able to state Ohm’s law, relate resistance to material properties, and solve real‑world calculations.

1. Do‑now (5 min): short quiz on definitions of V, I, and R.
2. Mini‑lecture (10 min): introduce Ohm’s law and the formula R = ρL⁄A with a diagram.
3. Guided example (10 min): work through the copper‑wire resistance calculation together.
4. Partner activity (10 min): use the resistivity handout to predict resistance of different materials and record results.
5. Concept check (5 min): think‑pair‑share on how temperature influences resistivity.
6. Summary & exit ticket (5 min): each student writes the law and one factor that changes resistance; collect for assessment.

Recap the key relationships: V = IR and R = ρL⁄A, emphasizing how material, length and area affect resistance. Students complete an exit ticket that reinforces the law and a factor influencing resistance. For homework, assign additional resistance calculations and ask learners to research the resistivity of a material of their choice and predict its usefulness in circuits.