Three discs on a vertical dowel

Three Discs on a Vertical Dowel asks a very young child for one thing: lift a disc, line the hole up with the peg and let it drop. Three pieces are few enough that the work can be finished, and finishing is exactly what a one-⁠year-⁠old is after; the vertical dowel puts gravity on the child's side, so a disc stays where it is put. Both hands work together while the eye guides them, which is the groundwork for every later threading and fitting activity. For children from birth to three.