Help with idea for a check-in and check-out system

I am helping a small youth camp to build up a check-in and check-out web system, so that each day people coming to the camp,they have to enter their code then check in, when they leave the section, they have to enter their code again to do a check-out

Basically, there are 8 sections. So each section will have two operations: check-in and then check-out

I do not know how to design the flow for this, can anyone giving me the idea how to design this flow?

I have a mysql table that has the names and the code of each student already.

I just need to track, when each student check-in and check-out for each section

Thanks for your help