Exercise and Video questions

How do I report mistakes in videos?

Why are Khan Academy videos not playing for me?

Why did I get the problem wrong when entering the correct math expression?

Why am I getting the problem wrong when entering the correct answer?

How do I report a mistake or issue with an exercise?

How do I enter math symbols in an exercise?

What happens to my Mastery and Energy points when I start an activity over?

Why can't I vote on a comment?

What are energy points, badges, and avatars?