I suggest noncooperative students be placed in a public-service program and spend their schooltime doing menial labor in municipal parks and buildings.
From the time.com
It is schooltime again, and across the land last week children gathered up their lunch boxes and book bags and boarded buses for school.
From the time.com
Then they learned that their gift would help children attend schooltime shows and fund arts education programming and teacher workshops provided to area schools by the Van Wezel.
From the heraldtribune.com
More examples
School: the period of instruction in a school; the time period when school is in session; "stay after school"; "he didn't miss a single day of school"; "when the school day was done we would walk home together"