Your progress is measured your progress in 2 ways:
Up Score, which measures your knowledge of the subject, your ability to recall information, and your overall mastery of the course.
XP (or experience points) which records the amount of productive time you spend on the platform.
Up Score is what tells you how much of the course you have mastered. It increases as you answer more questions correctly, and helps you understand how close to A* level you are.
Please note: The Up Score will increase to 60% when you have completed all the videos. This is when you need to start using the Practice Papers, and your scores in these will take you from 60% all the way up to that 90-100% A* level.