Can you find a rainbow?
The Basic Idea
Stick the tape onto the 'palette' to form 7 sections. Collect as many colours as possible from natural materials, perhaps grouping them according to the colours of the rainbow.
How to take it even further or make it more challenging
Count how many different colours/shades of one colour. See if you can name all the colours (good way to extend colour vocabulary). On another card palette, try to mix some of the colours using paint.