All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
There is no harm in helping the teacher with lawful requests such as buying textbooks, solving an equation using the calculator, or cleaning the whiteboard. In fact, helping the teacher with such acts is indicative of the student's noble character and commendable manners. The basic principle is that all things are lawful until proven otherwise by Sharia evidence.
Salmaan Al-Faarisi reported that the Prophet, sallallaahu ‘alayhi wa sallam, said, “The lawful is what Allah made lawful in His Book, and the unlawful is what Allah made unlawful in His Book. What He remained silent about is pardoned.” [At-Tirmithi and Ibn Maajah]
We hope that the Muslim will be rewarded for such acts.
We have previously underlined in fatwa 82431 that it is prohibited for the Muslim to study in mixed schools except for a necessity or dire need.
Allah knows best.