Questor produced a line of Sesame Street stacking toys in 1974 and 1975, under the Child Guidance label.
Bert and Ernie were released in 1974. Big Bird and Oscar the Grouch, a set of "Shape Stacking Toys", followed in 1975. The toys were each ten and a half inches high.
Each layer of the toys is a different, simple shape which must be matched to put them together. When fully assembled, the toys stand upright.