Charted Class E and G airspace:
The note in the legend that no one seems to see.
Class E starting at the Surface, 700 agl, 1200 agl, and non-standard altitudes.
Class G below 1200 agl, from the surface to but not including 14,500 MSL.
The mystery of the blue shading.
Teaching Airspace and Airspace Flash Cards:
The 5 cases (Memorization exercise).
Identifying airspace on a chart and standard dimensions.
Applying cloud clearances and visibilities.
Entry requirements and speed limits.