Khan Academy Extreme Frustration

Hi! I have been very upset for the past few months due to the amount of stress my teacher puts into khan academy in the classroom. He assigns 7-15 coach recommendations every week for us to complete. These assignments are one of the most heavily weighted things in our grade. These assignments basically are the be-all-end-all of his class. He doesn't teach the material in class and expects us to complete the time consuming and VERY tedious exercises. Do you think this is fair? Just because I cannot complete an online task means I should get a bad grade in the math class even though I have an A average in every other aspect of the class? Khan Academy is single-handedly destroying my well being and math grade. It is extremely frustrated and I wanted to see what you guys thought about it.