They did it for Loblaws, why not for schoolsThere should be little impact on labour, remember day on day off -- business would have access to child labour all year long, not just Jul-Aug. Also, the tax payer make work programs would need less funding if you didn't have to put the idle students on the gov't payroll.
As for A/C - I understand however the number of AC schools is greater then the number of AC homes. While it would be expensive to retrofit schools, it's a drop in the bucket with respect to the COVID spending that's gone on lately. JT can pony up a few billion chill dollars.
Central A/C may not work as schools weren't designed for it, but mini-splits in classrooms are simple with a few big MUA units for gyms/halls/offices.