Unit block

The unit block principle was popularized by educator Caroline Pratt in the early 1900s.

[1] Pratt based her blocks on a similar but larger-scale block system designed by educator Patty Hill, a follower of Friedrich Fröbel, the originator of kindergarten education.

Fröbel's series of 20 age-calibrated educational "gifts" had included a set of eight blocks, sized ½ by 1 by 2 inches, or a 1:2:4 ratio, which could be formed into a cube.

[3] In the 1970s, under license from the school, a version of the blocks was sold by a company called Childcraft.

Unit blocks vary in price according to the wood used and the manufacturer.