Leaf logic is ane exercise where the srudents agther as many different possible leaves. Then they try and form a Caroll diagram to sort the properties:

With older kids two way tables can be used to get more criteria.

Read the original at http://creativestarlearning.co.uk/maths-outdoors/leaf-logic/

Building on this idea you could look at leaves and the number of points; I think there will be a predominance of Fibonacci numbers.