Find a few different leaves with your child/ren and carve out some time to examine each leaf together.
Notice the color, the texture, trace your finger around the shape of the leaf, is it pointy/jagged/soft/crispy, etc? Look at the veins on the leaf, notice any holes on the leaf.
You can even explain the science of color in Autumn leaves. Here is a great article on this awesome science.
Ask your child/ren "If a leaf were a yoga pose, what would it look like?" Ask them to show you in their body what it would like. Do the pose with them. Make up your own. Get creative, share ideas and have fun!