What websites can I use to get games in my schools IPad?
Short answer you can’t download games outside of the AppStore, but, you can search on google for html games

NOT RECOMMENDED, doing this is on your own responsibilities  

And the long answer, you can download games from the Internet through Safari, but it’s (almost) only games that are breaking the law or for other reason isn’t allowed in the AppStore, they may contain malware/viruses, content kids shouldn’t watch or they may even steal your data.