> There's really solid evidence that increasing classroom time increases learning.

There's really solid evidence that intellectual performance drops sharply long before 40h/week. Unless the "classroom time" you talk about includes a lot of off-time and non-butt-in-seat activities it seems you'll be deep into diminishing returns if not outright losing if you increase the length of the school day. My own memories of schools are that by late afternoon many students had stopped following altogether.

As long as you pay teachers overtime for all the extra hours they'll be working to put together curriculum for your longer school days, I'm in. It's not just students who have to be working during those hours, it's also teachers.

Read both sentences before getting ultra snarky please.