Children learn to make connections and associations. The "Things that go together" set includes a "Why" card.

When a child can visually see why things go together, it all makes sense. Attach and detach the laminated cards as needed. You pick the first card and the child picks the association and reason why card.

Alternatively, you can pick the "Why" card and the child finds the associations and attaches them using Velcro. Lots of different options are included which make learning this skill easy.