Throughout Covid-19, my youth group decided to meet up and participate online together!
We used a program called discord to call/face time. This also allowed us to create a private “server”, where text or voice channels can be created for different situations.
We used a text chat to post ideas for improving the server, and another one for future events once covid is gone.
Often “bots” can be added to provide extra support with running the server or playing educative games.
While we used the bots for biblical knowledge tests, you could also have a math tester/assistant, spelling, you name it.

I would 100% recommend discord as a community group that allows students to connect with each other and participate easily.