Issued Patents All Time
Showing 1–5 of 5 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 5238407 | Blocks with mating bosses and recesses which bulge for interference fit | — | 1993-08-24 |
| 5238408 | Row of joined arithmetic blocks with common walls which are double end wall thickness | — | 1993-08-24 |
| 5176577 | Rectangular blocks for teaching arithmetic have uniform size joinability and transparency | — | 1993-01-05 |
| 5137452 | Base--ten blocks employing single, attachable blocks of one color row of ten blocks of different color | — | 1992-08-11 |
| 4379700 | Multiplication/division tutorial game | — | 1983-04-12 |