I always figured the wax melts were the easy route and the stove pot was just something people did to feel thrifty. Turns out I had it backwards too. Apple peels and a cinnamon stick lasted through the whole evening for me, and the house smelled like it all the way to the stairs, not just the one room. Rosemary goes strong for the first hour but then fades, so I'd stick with the peels if you want it to hang around.

Cucumbers in the middle and crackers at the edge sounds dumb simple but it probably works. Kids just grab whatever's closest to their hand, and adults are the same way honestly.

Six calibration checks a season is a lot of money and downtime for something a five minute talk could fix. Do the instructors actually check the clickers at the end of each class, or does the tool crib just eat the cost and nobody says anything? If the schools are not watching it, the habit just walks out the door with the students.