My girls and I got out the red, yellow, brown and orange construction paper the other day and made some largish falling leaves to go around our kitchen. It's easy as pie (Wait, pie can be hard. Who started this saying?). It's as easy as falling off a log (wait, maybe it is a bit harder than that). Ok, I'll let my southern roots show: It's as easy as all get-out, and fun to vary the shapes of the leaves. Good scissors practice too.
I brought out my small hole punches at some point and suggested they make a couple of tiny holes in some of the leaves to make it seem more realistic. I left the room for a moment and when I came back it looked like the leaves had been sent to the front lines and the enemy had a Gatling Gun. Oh well. Go with the flow. They had fun.
We are really enjoying having the (holey) falling leaves inside, since there aren't that many outside yet. We taped some on our china cabinet and hung some from the doorway with thread. They twirl around on any stray puff of air.
I recommend you make some with your kids and festoon the house with them:
1) Fold a sheet of construction paper in half, longwise.
2) Draw a simple arc shape. You can also do pointy and curvy ones. Vary the sizes.
3) Cut along your lines.
4) Unfold and draw on leaf veins. Or bugs. Or a unicorn (this was my youngest's suggestion).
5) If desired, use a small hole punch to accent your leaves with a FEW, artful tiny holes along the edges.
6) Make many. Dangle them from doorways by taping several to a long piece of thread, and use low-tack painter's tape to stick them to various things, including your children.