More categories could include;
- Geology - What Sport
- What kind of tree - Famous Perons
- Matrices - Wars
- What era - Biology
- Fashion - U.S. Presidents
- Governments - History (Modern/Ancient)
- Politics - Animals
- Rivers of the World - Religious Studies
- T.V. Charcters - Astronomy
- Physics - Molecular Compounds
- Geomorphology - Volcanoes
- Oceanography - Fishes
- Plants - Farming
There is so much out there and I haven't even begun to scratch the surface, but I would appreciate it if you could add a couple of these in.