Year 7 are learning how substances move into and out of cells by diffusion. At the end of the previous lesson the class set up a beaker of still water with a ruler taped behind it and a clock in shot, and the teacher, wearing gloves and goggles, dropped a single crystal of potassium permanganate into it with tweezers. A school tablet on a stand filmed the beaker overnight in time-lapse. Today the teacher plays the footage on the board: purple colour spreading slowly out from the crystal over many hours, squeezed into under a minute. The teacher replays it, pausing at regular clock times so students can read how far the colour has spread, and students plot distance against time in their books and explain, using the particle model, why the spreading slows down.
Tools: Built-in camera (slow motion and time-lapse) Nine ideas for your own version in Generate
This page is one of a growing set of PICRAT examples by cell, subject and grade. Page maintained by Andy Perryer.