At my stepson's previous school, they had an ID card, which they had to put into a scanner when they got to their registration class in the morning.
The biggest problem was that the learners often forgot their cards at home or lost them.
In the end, they went back to the old way of the teacher reading the names from her register and then marking them.

I am sure that in the near future we might even see chips being inplanted and used for things like this. (•ิ‿•ิ)

Best wishes!