Yes, all your students can start at a level best suited for them. Have them take a Skill test (Try to unlock level X) in the syllabus. They are designed to determine the skill level for each student. Upon successful completion of a skill test, all previous content in the syllabus is unlocked.
If a skill test is too hard, they should try an easier one. Conversely, if a skill test is too easy, they can play a harder one. This way, every student can find their level and progress on from there.