Mark, capture, release

One of our teachers wanted me to set mouse traps around the school grounds to capture mice for him to show the kids...when I mentioned possible risks from rodents and leptospirosis he said it was okay cos I would be handling them not the kids! So I used the excuse that we might accidentally trap shrews without the correct traps and that's illegal (cos they die really quickly without food). So he ummed and ahhhed a bit so in the end I just refused to provide any traps......(we need a shaking head in exasperation emoji)
Would acrylic paint spots work? It dries quickly and once dried is not affected by water.

(I agree you must release Mark after capture - it would be cruel otherwise!)
I have seen research papers using nail varnish for woodlice, release mark capture, even down to them specifying the brands. However, we have always used laminated cards and hidden them around labs instead. Boring but definitely ethical.
Pasta shells, brown paper take away carrier bags and marker pens, works fine for the Lincoln Index, with all the hot weather I think the woodlice are best left alone in the dark damp hidey holes they have found, plenty of other biology activities that can be done outside involving plants at this time of year rather than trying to find anything growing in the winter.