Lesson Plan

• Describe how to plot magnetic field lines using a compass.
• Explain how iron filings reveal the shape and strength of a magnetic field.
• Use a compass to determine the direction of the magnetic field at any point around a magnet.
• Compare the accuracy and practicality of the compass and iron‑filings methods.

• Bar magnet (or horseshoe magnet)
• Small compass (low‑friction pivot)
• White A4 paper and pencils
• Fine iron filings or steel‑wool shavings
• Shallow tray or transparent sheet
• Cardboard to protect work surface
• Worksheet with diagram prompts

Begin with a quick demonstration of a hidden magnetic field using a hidden magnet under a sheet of paper. Ask students what they already know about magnetic poles and field lines. Explain that by the end of the lesson they will be able to plot field lines accurately and use a compass to read the field direction.

1. Do‑Now (5'): Students label north and south poles on a printed magnet diagram and write one prediction about how a compass will behave near a magnet.
2. Teacher demo – compass method (10'): Show the step‑by‑step procedure for tracing a field line with a compass and pencil.
3. Student activity – compass tracing (15'): In pairs, students repeat the procedure from several start points, recording each line segment.
4. Group activity – iron filings (10'): Teams sprinkle filings on a tray with a magnet and observe the continuous pattern.
5. Comparison discussion (10'): Groups compare the two methods, focusing on accuracy, visualisation of strength, and set‑up time.
6. Misconception check (5'): Quick quiz on common errors (e.g., field lines are physical objects).
7. Exit ticket (5'): Students write one sentence summarising how a compass indicates the direction of B at a point.

Review the key steps for plotting field lines with both methods and reinforce that the compass needle aligns with the local magnetic field direction. Collect exit tickets and assign a short homework task: students must sketch field lines for a horseshoe magnet using either method and label the direction of B at three points.