Set up your home router to use
OpenDNS Family Shield for it's DNS servers. The kids probably don't have admin rights to change the DNS on their school laptops so it might be enough. You can manually change the DNS servers back on your own devices if you want to access adult / gambling / whatever sites blocked by the family shield.
Now if your kid has a phone all bets are off. They can get off wifi and avoid your network restrictions altogether. The phone carriers do usually have a family filtering service you can set up, and so do Apple and Google phones. You'll have to research based on what devices your family uses.