When exploring angles a Clinometer can be an excellent tool. They are relatively cheap and they give really useful reading from which children can draw triangles from the observer to a tree.
Concepts which can be investigated are:
1.The angle need to build a flying fox. Then constructing a drawing of the flying fox.
2. The angle a cannon would have to be pointed on castle ( introduce projectile as a straight line first)
2. The ideas of how this angle may help to determine height can be explored with older children.
makingpi 