A hands-on enrichment kit — posters, activity cards, student sheets, and a song — for a child's first big idea in science: things that belong together get put together.

A category is things that belong together — and the same pile sorts many right ways, depending on the attribute you notice.
⬇ This card
The sorting rule lives in the sorter's head — and a careful watcher can figure it out from the evidence alone. That is what scientists do.
⬇ This card
One thing can belong to two categories at once — it stands in the overlap. A real Venn diagram, big enough to stand in.
⬇ This card
Organization powers memory — Nebel's own proof. Sorting the tray in your head makes the recall number jump, and the kids measure it.
⬇ This card
Groups hold groups: categories subdivide into subcategories and combine into bigger ones. A tree diagram grows live on the board.
⬇ This card
Anything can be sorted — and the house is already full of sorting somebody chose on purpose. Once you see it, you can't stop seeing it.
⬇ This card