A low-lift invitation: leaf, paper, crayon.

I want to be honest about the phrase no prep, because it is usually not true. There is printing. There is finding a leaf. There is an adult nearby, and afterward there is a table to wipe.

So here is the real list. One flat leaf, still bendable. A sheet of plain paper. A crayon with the paper peeled off. Ten minutes. An adult willing to hold the corner of the page.

That is the whole thing. Early-childhood guidance supports the idea that a short neighborhood walk can raise good questions without a formal lesson behind it, and this is the smallest version of that I know.

If you want a second step, it is only this: ask where the leaf came from and go put your hand on that tree. It turns a craft into an observation, and it takes an extra two minutes.

If you do not have crayons, a soft pencil works. If you cannot pick anything, a rubbing of bark or a sidewalk seam works. The activity survives most substitutions, which is why I keep coming back to it.