Looking for an easy ADHD friendly way to track attendance for classes.

Hello,

I teach classes at a community hall and I've been struggling to reliably track the number of students in my classes. I teach 2 classes back to back and have to put the chairs away after the first class (chair yoga 45 mins) and prep for my next class with a 10 or 15 minute gap in between. There are 2 different rates that I charge and I need to track 2 sets for both classes. I have a spreadsheet on google sheets but I try not to be on my phone before class or at the start.

Anyone have things that worked well for them? I bike to my classes so any additions will have to be light and highly portable.

Thanks in advance.