Classes should be pretty specialized (IMO)

something like:

-beginners Hydro - Ebb and Flo - lean to make a complete system with take home parts list
-beginners Hydro - DWC/Bubbleponics/aeroponics (learn to build a recirculating dwc system with all parts needed for a 6 plant system)
-beginners Soil/Soiless/Organics
-beginners Outdoor - from gurilla to back yard

Intermediate:
Nutrient Requirements during veg and flower and examples with general hydroponics and advanced nutrients (1 or 2 versions for hydro + soil(less))
Proper Lighting + Ventilation for grows over 4K watts - lumens per square foot, bulb quality & lifetime, cooling systems

just some ideas to spread out the crowd some and make people happy by hitting on their subject..