The potato vines spilling over the top of our potato bag had gone brown and dead about two weeks ago, so we figured it was time to harvest the potatoes. By "harvest," I mean, "dump the bag in a bare patch of the yard, then use a pink Disney Princess trowel to sift through for potatoes."
We got a decent amount of baby yukon potatoes from the three or four we originally put in the potato bag. Trix and I would rake and dig -- naturally, the Disney Princess trowel comes with a Disney Princess hand rake -- and after a while, Trix asked, "How did the plant make more potatoes?"
"The plant turned dirt and water into potatoes," I said. "That's the miracle of plants. They turn dirt and water into food."
I did not think it was entirely necessary to talk about the mechanics. There will be time to talk about how a plant's root system selectively absorbs nutrients, then pushes the ions into the sap that the xylem (i.e. one of a plant's vascular networks) will then distribute through the plant. We'll probably end up making a poster about photosynthesis at some point in her school career.
For now, it's amazing to have proof that plants can turn dirt and water into food. And it's even more amazing that we live in a world where people have been able to ask and answer the question, "But how does that plant do that?"