Instead of students going to class on a daily basis, what if students were in charge of their own learning. They could make decisions as to what courses they want to take and utilize the power of the internet, libraries, etc. to learn. The proof of their education could come with a comprehensive exam for each subject that students could elect to take at certain points throughout the year.
The exam offered does not have to be a typical standard examination like the SAT or ACT. The exam could include questions about key concepts that an expert in the subject should know, but also an essay section where the student can write about how they could apply what they have learned about this subject in real life or an idea they may have about taking a certain idea in that subject forward to discover new things. This essay portion serves to show the examiner that the student has mastered the subject well enough to be thinking about how they can make advances in this field.
This would be an interesting way to learn since students could learn what they want and show off their knowledge in an exam that fosters some sort of intellectual creativity.