Identifying trees by their leaves can be an enjoyable and interesting activity for both children and adults. If you teach children the basic steps of leaf identification, they can learn what to look for on a leaf and then can figure out what species a tree is by its leaves. Encourage kids to collect a variety of leaves and then figure out what kinds of leaves they have by their shapes and sizes.
Take a leaf walk, collecting leaves from trees as you walk. Choose leaves that appear whole and unblemished, placing them in your sack as you walk. Take the leaf sack back home, and promptly remove the leaves to identify them. Spread the leaves out onto a flat surface, and choose a leaf to identify first.
Examine the leaf to determine whether it is from a coniferous or deciduous tree. Coniferous leaves are thin or flat; these are the pine needles of evergreen trees that do not turn colour and fall in the autumn. Deciduous trees have wide or broad, flat leaves that turn colours in the autumn and then fall to the ground.
Look at the way a leaf grows on a stem. You might see one single leaf that grows on the end of a stem; this is called a simple leaf. As well, you might see many leaves that grow together along one stem. This is called a compound leaf.
Check the outside edge of a simple leaf. A leaf might have lobed edges that appear irregular around the edges, the lobes might be symmetrical, or there might not be lobes at all. Notice whether the edges are smooth or serrated with small teeth. These characteristics will help you determine which species the tree is.
Examine compound leaves to see how they grow along the stem. You might find them growing all together on the end of a stem or along both sides of a stem (pinnately compound). Notice the leaf edges to see if they are smooth or serrated. Also examine the shape of the leaf, which can be round or pointed. These characteristics will help you determine which species the tree is.
Consult a tree book or a website that offers identification help after you match up the leaf characteristics you've noted with the species of the tree it came from. The Ohio Public Library Information Network's website, for example, offers assistance identifying leaves according to individual characteristics.
Label leaves after you identify them, so you and your children can learn what different leaves look like and remember them after you identify them.