What is leaf arrangement?

Leaf arrangement refers to the branching pattern of trees. Leaves and branches grow from the stem either exactly opposite from one another or are staggered which is called alternate.

How do I know if leaves are simple or compound?
The secret is to look at the buds. The buds for next years growth will appear at the base of the leafstem. Leaflets do not have buds at their base and are therefore part ofa compound­ leaf. A twice-compound leaf is a leaf that splits twice before fonning leaflets.

What are leaf margins?

Leaf margins refer to the edge of the leaf. A leaf  margin can be smooth or have teeth. It can also be lobed or unlobed. Any combination of these characters can happen also.