You should pray maghrib on time, it is not acceptable to delay it past its time everyday for this reason. I didn’t understand your justification. Never the less, you can go out to answer the call of nature for few minute. You can Pray outside the class room.

I am studying at an institute in Dubai. Because of time changing I am missing my magrib salah. I cannot leave the class and go as it is mix and the day I don’t go to pray they will doubt. I have no choice except to join magrib with isha. Isha is offered on time. Is this okay?