Years ago my family had a set of wooden cubes for large construction. Since they were completely enclosed, they were difficult to grip. My dad watched my brothers and sister struggle with these cubes and thought there must be a better solution. That's when he had the light-bulb moment – blocks with open sides. It seems obvious today!
It was 1954 when my father came up with his breakthrough hollow block design. He and his co-workers at Community Playthings decided to base their new hollow block on the same mathematical principle as the unit blocks they'd been making since 1947: the length being twice the width, which was twice the depth. Since hollow block and unit block dimensions are modular, children love using them together.
The best product design is always based on observation of children's play. I often see children playing with Hollow blocks when I visit settings, and it always reminds me of my dad.