I have taught such interactive classes/labs by myself. If you have prepared enough, i.e. have a very solidly laid out worksheet of appropriate difficulty, then

I have taught such interactive classes/labs by myself. If you have prepared enough, i.e. have a very solidly laid out worksheet of appropriate difficulty, then a single person can handle about 20 people. About 5 students will have no problem and you just need to quickly check on them once or twice. 10 will need quick interventions. 5 will need more support. You can probably do three rounds in that one hour.