MathElf does not officially support any non-math subjects. Apologize and let your student know that they can come back and talk to a tutor when they need help with math.
We have, occasionally, helped students in some science subjects in booked sessions. If you are comfortable helping your student with the topic they'd like to work on, feel free to do so. Let them know that they can book future sessions or reconnect with you to work on this subject later, but that they won't usually be able to get help in non-math subjects on-demand.
You can direct students to email firstname.lastname@example.org if they'd like to ask about the possibility of getting help in non-math subjects through MathElf. We may be able to book a session for them. If not, we can be the ones who disappoint them instead of you.