Kahn Academy, a non-profit, has been helping students and teachers with their lessons for many years now. They've just added a heavily curated and controlled AI capability to their toolbox. So you might find this helpful with your school age kids. And the price is only $9/month.
If you can't get to the link because you don't have a linkedin account, try this announcement of his:
Big news. Share with parents who want cutting edge support for their children this school year! We are opening access for the next 20,000 parents to now get their children access to the world's most powerful and safe AI tutor - Khanmigo.
We need to charge $9/month to pay for the computation costs.
Sign up here: http://khan.co/khanmigo-parent