OK, that tree-identifying game is not awful, BUT...
@TamarYaelBatYah , you write from a parent's perspective. Why rely on a tree identification book? Take them to one place, show them the tree, let them see leafs, let them touch the bark and see the texture of it, show them nuts and tell them if they are edible. Use the opportunity to bond with the kids. Then take them somewhere else and ask them to find that type of tree. Make it harder, like: show them a green maple tree and let them search somewhere where red ones grow - that's another fun learning experience and an opportunity to explain something. You omit that bonding part entirely and that's the main purpose of doing stuff together.