- In addition to the "like terms" practice, these activities provide a welcome algebra-geometry connection.
 - In particular, working with concrete materials is far more effective than looking at textbook illustrations when introducing surface area.
 - And here's a bonus challenge. Using three blocks (not necessarily all different), make a Lab Gear building for each of these surface areas: 
- `2x^2+12xy`
 - `6y^2+8xy`
 - `6xy+8x^2`