# I already know how to multiply

January 20, 2015 8:17 AM Subscribe

I'm re-learning calculus using Khan Academy, and I find it great except for one thing. The "Mastery Challenge" keeps going over things I know perfectly well. How can I make it skip that stuff?

For example, "Adding within 5." Thanks, but I think I got that. As a more serious example, it keeps asking me to simplify rational expressions. Those kinds of questions waste a lot of my time, and I often mess up not because I haven't "mastered" it but rather because I make a stupid mistake (which I will never ever not do).

How can I prevent certain kinds of questions from showing up in my Mastery Challenge? I have set myself up as a parent and a coach to myself but have not yet made any recommendations or anything.

I posted this same question in two Khan Academy forums, but those seem like cesspools of soccer-related spam, so I figured I'd try my favorite advice site too. Thanks in advance.

For example, "Adding within 5." Thanks, but I think I got that. As a more serious example, it keeps asking me to simplify rational expressions. Those kinds of questions waste a lot of my time, and I often mess up not because I haven't "mastered" it but rather because I make a stupid mistake (which I will never ever not do).

How can I prevent certain kinds of questions from showing up in my Mastery Challenge? I have set myself up as a parent and a coach to myself but have not yet made any recommendations or anything.

I posted this same question in two Khan Academy forums, but those seem like cesspools of soccer-related spam, so I figured I'd try my favorite advice site too. Thanks in advance.

Mod note: Folks, it's okayish to have the "this is why it's important to be able to do that stuff, though" angle aired but the actual question's pretty specific and we need to have folks either answer it or not from here in.

posted by cortex (staff) at 10:53 AM on January 20, 2015 [1 favorite]

posted by cortex (staff) at 10:53 AM on January 20, 2015 [1 favorite]

Response by poster: Maybe I should have been clearerâ€”I don't "often" make such mistakes, but they happen on occasion. I understand that if I'm not PERFECT at algebra, then I'm not going to be PERFECT at calculus, but I don't tie my "success" in calculus to being PERFECT at it. I got A's in AP BC calculus (plus a 5 on the AP test) back in high school making the same kind of dumb mistakes once in a while, and I considered that 100% successful.

posted by dondiego87 at 12:28 PM on January 20, 2015

posted by dondiego87 at 12:28 PM on January 20, 2015

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As a more serious example, it keeps asking me to simplify rational expressions. Those kinds of questions waste a lot of my time, and I often mess up not because I haven't "mastered" it but rather because I make a stupid mistake (which I will never ever not do).If you can't successfully simplify rational expressions correctly, then you're going to get the calculus problems wrong that depend on such simplifications. I totally understand about making stupid mistakes, but respectfully, you should be getting the basic algebra right almost all of the time in order to be successful at the calculus. I say this as a calculus instructor---it's not the calculus that trips people up, it's the algebra.

posted by leahwrenn at 9:06 AM on January 20, 2015 [9 favorites]