I came across this leaf counting activity from when I taught in a Montessori preschool previously. It was nice to actually pull something out that is ready to go on the shelf since I've been so busy making new things.
Here is the work on a tray. Sorry for the glare. There are 10 trees numbered 1-10. They are cut from construction paper and laminated. The leaves are also made from construction paper and laminated. There are 55 leaves, exactly enough needed for the activity.
To do this activity, the child lays out the trees in numerical order on their rug as shown in the first photo. They then place the correct number of leaves on the branches to match the numeral on the tree trunk. The second photo shows trees 1-3 close up.
If I was going to make this activity from scratch today, I would consider using felt for the trees. You can now buy "stiffened" felt and that would make a nice base. I would then use fabric paint to write the numerals. And I would use some of the really cool felt leaves from Hobby Lobby for the counting leaves. Maybe if I ever open an Etsy shop, I'll consider making this activity up to sell.
NOTE: If you were using this activity with a child who didn't know numbers 1-10, you could just do fewer trees or only use the trees 1-3 or 1-5 or whatever, depending upon their skill level.