What type of China Visa can I apply if I am going to volunteer in China, not work in China?

i have a school which i applied to volunteered with the School,fortunately for me i was picked to volunteer.An invite was sent to me from the school and some from the Government.My invite did not a working permit which i believe is simple because the contract is base on volunteering not working.But when i was at the embassy i was asked to provide a working permit form the government.i told my school and they are now telling me that for the fact that im not coming there to work i don't need a working permit and that i only need an invite.i don't know what to do right now.Do i really need a working permit as im going to volunteer but not to work for my Visa