This is an excellent resource for teaching Scale that was shared on Twitter by Graham Linehan last week.
This Cell Size and Scale interactive from the Genetic Science Learning Centre, University of Utah, takes you from a coffee bean down to a carbon atom.
Drahg the slider across the screen to zoom in and out and view cells, organlles, paramecium, viruses and molecules, ending with a carbon atom. It’s a brilliant, clear way to demonstrate relative scales of objects and would be perfect for Science teachers. View it here