"Hey, would it be possible to do this online?" "Is there an online option?" "Is there any way we can switch to online? I would rather be safe, and I'm a little worried because one of our teachers tested positive and it led to a closure (ちなみに 学級閉鎖とは具体的にどのような状況ですか?). I would hate for that to happen to ____. I apologize for any inconvenience."
"Thank you for your time" か "understanding" か "time and attention" はイーメールでよく使いますね。
Hello, One of our teachers had to close his(her) class due to Covid. In order to avoid possibilities of any other spread, we would like to do lessons online until further notice. We apologize for any inconvenience.