Fifty schoolchildren and their parents have been stopped and questioned by police at Manchester Airport for going on holiday during term time.
The truancy checks are happening because a growing number of parents are booking cheaper out-of-season family trips.
So education chiefs in Manchester are cracking down and warning parents they must get permission from the school first.
It's the first scheme of its kind in the UK and was launched after complaints from schools.
One education boss in Manchester, Councillor Bernard Stone, said: "One day missed from school is too many."
If parents keep taking their children out of school they could face fines of up to £2,500 for each child.