Maybe they are trying to prove how false the tests are.
Not sure how well known that trick was, but I am sure they figured out what was going on over time ;)
Point is kids will be kids and may just want a day off because beautiful weather or big test for which they are unprepared...
Positive Covid test fits the bill...and get not just a day but a vacation week or two!
Ok I think its just kids messing with the test in order to get out of school.