Magnetic Field Lines in a Bag
Filings form curved patterns.
Teaching & key ideas
What you do: Move magnet beneath sealed filings.
What students see: Filings form curved patterns.
Why it works: Each filing aligns with the local magnetic field.
Question to ask: Can we see an invisible magnetic field?
Lesson flow
Predict → demonstrate → observe → briefly explain → ask: Can we see an invisible magnetic field?