Clickory

Classroom mode

Run it in class

How can soap change the pull across a water surface?

Show of hands — before you project anything

Predict first: the surface of water acts like a stretched skin. What do you think happens to that skin right where a drop of soap lands?

  • A Way more than you'd guess
  • B About what you'd guess
  • C Way less than you'd guess

Count the votes out loud. Hold them to it — then watch.

Project it (fullscreen)

Discussion prompts

  • Predict first: the surface of water acts like a stretched skin. What do you think happens to that skin right where a drop of soap lands?
  • Predict first: when soap weakens the skin in the middle but the edges are still strong, which way will the surface get pulled — and why?
  • Predict first: if you stir the soap all through the water, will the pepper keep racing, or stop? What's different about the skin now?

Where it shows up in real life

  • A water strider standing on top of a pond
  • Water bulging up over the rim of a too-full glass without spilling
  • Round beads of water on a freshly waxed car or a leaf

A prediction-first worksheet — no answer key.

zero prep · no login · any projector

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