What is the proper way of looking into a compound microscope?

Should it be something like keeping both eyes opened or only one eye is opened (the eye looking through the microscope). We had an experiment today about compound microscopes and there was one question --"Why is it important to keep both eyes opened when looking through a microscope?" I was wondering because I think the proper way is one eye should be closed while the other eye is opened as it looks through the eyepiece. help me! im so confused...