If you're not initially placed in the courses you want, don't give up! Advocating for yourself is a valuable skill.
Request a meeting with your counselor and/or the teacher. Be respectful but persistent:
"I understand the normal placement criteria, but I believe I'm ready for [course] because [specific reasons]. I'm willing to [put in extra effort/take a placement test/sign a contract] to prove I can handle it."
If the answer is still no:
Advocating for yourself is a skill that will serve you throughout life!