Use your senses. What do you see? Hear? Smell? Feel? What is the weather like? How many birds can you see? Can you hear rustling leaves? leaves blowing and falling? leaves crunching? birds chirping? Can you find any animal tracks? How many different color leaves can you find? How many different leaf shapes? How many textures? Can you find something smooth? Something rough? Something cold? Something wet? Can you feel the warmth of the sun? Can you feel the wind?
Collect acorns, pinecones, seedpods, leaves, rocks, or anything else you find interesting and bring them home to display as a collection. See if you can identify the things you collected.
Any time you are able to spend outdoors will be time well spent. Having that connection with nature is so important, not only for children, but for us adults as well. It sort of reminds me of a quote that I recently read in Ralph Waldo Emerson's book Nature, "The health of the eye seems to demand a horizon. We are never tired, so long as we can see far enough." Isn't that so true? Something about being outside is energizing. When we can see all the way to the horizon without the clutter of people and buildings and cars it is refreshing. At least for me, it feels easier to breathe.