Khan Academy tracks mastery on a skill-by-skill basis. When you first start using Khan Academy, you’ll be at the needs practice level on every skill. As you answer math problems, Khan Academy’s adaptive software learns what you know and adjusts your mastery level on each skill.
We encourage you to make mastery your goal!
Note: It is possible to move backwards in levels by answer questions wrong. Keep practicing to keep your mastery level up!
See also:
The Mastery System
What is the mastery system?
How does Khan Academy measure my math knowledge?
How can I see which skills I’ve mastered?
How does the mastery system help Khan Academy personalize my learning experience?