Sticker line-up

Hand the child a sticker sheet and any paper (a junk-mail catalog works great).

Peel one sticker. Stick it in the corner of the page. Peel a second. Stick it next to the first.

A 2-year-old will sticker their own arm; a 3-year-old will start covering the page edge-to-edge; a 4-year-old will line stickers in deliberate rows, often with a logic only they understand.

Provide a grid (or graph paper) so they fill cells one at a time. Make a "sticker story" — line them up to tell a sequence.