To clarify
- the 20 pushups is pointless if they can't do 1. That was my corollary - no point telling a 40 year old man to do an oversplit if he is nowhere near a regular split.
- No need to move the foot IMO. I say "put your foot here" and point to the spot.
- You can do the same drills with a smile or a frown. A smile will have people staying with the school more frequently than a frown. E.g., an advertisement for a kids' programme never has a picture of a master with a frown. It's always smiles.
Here is how I would like to start a class