Excellent question and glad you asked. The other nurses already answered the census question. You and your class will also be affected by a low census. If the census drops hospital wide the hospitals will send clinical groups home, then start sending their nurses home since there would be no unit to float to.
There can only be so many types of students on a floor at a time per licensed discipline eg: nurses, physicians, respiratory therapists, etc. So there are nurse : pt ratios, student nurse: licensed nurse ratios, student nurses: per clinical instructor, medical student: doctor ratios. In my state no more then 12 nursing students can be assigned to a single instructor for a clinical group. If the group exceeds 12 d/t rotation placement then the schools will sent 2 instructors to teach the one clinical group.