Simple 4-piece puzzle to introduce baby to foundational concepts in topology, convexity, symmetry, chirality, set theory, regular polygons, dimensionality, geometry, Boolean operations, entropy, and other mathematical areas. Also works as a toy.

Pieces have beveled sides for extremely easy placement by babies and toddlers with imperfect motor skills.

At full scale, pieces are large enough to not pose a choking hazard.

Update 2/18/2018: Slightly increased size of triangle piece so that it won't fit into the circle or square slots. Also looks more proportionate with other pieces. Corresponding adjustments were also made to the base. Note that the photo is still of the old version.