Can my college professor legally give me a final grade of 0 for not completing observation hours? (Sec ed)?

Basically I am doing very well in the cl. It is really 2 cles combined into one, GE and ELL teaching (A) and then SPED (B). Each cl is said to be worth 50% of grade. So, I expect an 85% in SPED and will have approximately a 90 in the other cl. However, I plan on switching out of education and did not put in for my clearances. Therefore, I cannot complete the clroom observation hours needed for cl A. I spoke with the professor and was told I automatically have a zero on my report card because I did not complete these hours. The way I am looking at it, I have a total of 7 exams in this class, quite a few graded assignments, good attendence, etc which all of this time has been helping my grade. How can all of this work be simply forgotten about? I could understand that it is a requirement to become a certified teacher, but I am changing majors. I cannot afford to fail a 6 credit class my first semester. Is there anything I can do? Thankyou.