Demonstrate how clouds make rain.
Selection of jam jars, liquid food colouring, pipettes and shaving foam.
I would do this in Beaver lodges, so will need four sets.
Fill jam jars to about 2/3 with tepid/ warm water. Squirt on shaving foam to cover (this is why you need several jars, they will all want a go. Add drips of food coloring with a pipette. This allows each Beaver to add colour and each experiment will be slightly different. Watch as the rain comes through the cloud, once the cloud has enough water in it.
If using paste colours dilute.