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  • - So this is Sal Khan, founder of the Khan Academy.

  • And this is a very exciting Skype call that we're on.

  • I'm with Ben Hedrick,

  • who's the lead for AP Calculus.

  • What do you at the College Board?

  • - Really, anything with AP Calculus and AP Statistics

  • is something that I have a little bit of control over.

  • So for example, for AP Calculus,

  • anything with the curriculum, anything with the assessment

  • is something that I work with.

  • - And I'm sure that you're as excited

  • as I am and, you know,

  • several hundred thousands of students are around the country

  • for the AP exams that are coming up

  • in roughly a little less than a week.

  • And I thought a fun place to start would be

  • when you guys write the test,

  • what are you trying to assess?

  • What's the spirit of the questions?

  • Both on the multiple choice and the free response section.

  • - So what we're looking for from students

  • is evidence of good, conceptual understanding in calculus.

  • Now, we have some things that are gonna test procedures,

  • but really, we want students to understand what's going on

  • with the calculus rather than just calculating things

  • or putting numbers on paper.

  • A lot of thinking questions, a lot of insight

  • to make sure that whatever good calculus those students

  • have learned in their courses,

  • we're assessing it on the AP exam.

  • - And I've done a bunch of example problems for the AP exam,

  • and yeah, my sense of it is

  • you sometimes will do some of the minutiae work

  • or you'll give the formula,

  • and you're really trying to understand

  • whether students understand the essence

  • of what an integral is,

  • or the essence of derivative as a rate of change,

  • or the slope of a tangent line.

  • So, if you were preparing for this exam,

  • if you were the students,

  • what you suggest to them?

  • You know, obviously we have a little less than a week

  • for this current test,

  • so what advice would you have for those students?

  • And then just generally, as students go through the year,

  • how should they think about it?

  • - Yeah, the advice I would give

  • is dependent on how much time the students have

  • to prepare, so the advice that I give

  • at the beginning of the year is different from the advice

  • that I give now, several days before the exam.

  • Getting ready for it, first, relax.

  • You know, this is a calculus exam.

  • We're not gonna be throwing anything at you from left field.

  • It's calculus.

  • You need to know limits.

  • You need to know derivatives.

  • You need to know integrals.

  • In terms of preparation, make sure you're taking the time

  • to review the basics.

  • Every question that they see

  • is gonna hit one of those big topics,

  • so make sure you know your derivative rules,

  • make sure you know your integral rules.

  • Take a look at the old exams

  • and see how we're asking questions.

  • And you'll at the patterns and see that we're always asking

  • about understanding what a derivative means,

  • understanding integration or the idea of accumulation.

  • There are no secrets on the exams,

  • so really stick with what we've done.

  • Make sure that you're thinking of ways

  • to apply to your good knowledge,

  • and just review your basics.

  • - And my experience with the exam is there's a lot of,

  • as you just said, really the mainstream, meaty topics.

  • You know, chain rule, fundamental theorem,

  • or theorems of calculus, things like that.

  • What's your sense of the more,

  • what I would concern maybe a little bit more, the minutiae,

  • some of the more special case derivatives,

  • or special case integrals, you know, arc tangent and,

  • how much does that play into the exam?

  • - You know, I think, Sal, you've actually answered

  • your own question in asking that,

  • is it is the minutiae.

  • So really, at this point in time, if you're getting ready

  • for the exam, spending time on minutiae

  • is not where you're gonna be best served with your time.

  • You should be hitting the major things,

  • and you said it right at the beginning, chain rule.

  • I mean, any kind of question we do with derivatives,

  • you know, if you're doing maxes or mins,

  • if you're doing tangent lines,

  • if you're doing a related rates problem,

  • they're all derivatives, derivatives, derivatives.

  • And if you're having trouble with chain rule,

  • it doesn't matter how much minutiae you spend time with,

  • the chain rule's gonna come up.

  • So I would say don't sweat the minutiae.

  • There might be something on the exam

  • that you haven't reviewed as much as you want to,

  • but it's gonna be one single, solitary question.

  • Basic derivatives are going to form, well,

  • the basis for all those problems.

  • So that's where your time is best spent.

  • - Yeah, I definitely get that sense.

  • Especially, you know, how do you interpret the first,

  • second, you know, derivatives, concavity.

  • Things like that, those seem to show up a lot.

  • But once again, that's a conceptual idea of derivatives.

  • And on the integration side,

  • I've been doing a bunch of the free response.

  • It just seems like, I mean, you know,

  • what happens if you swap the bounds of integration,

  • or if you add integrals.

  • So a lot of the properties and the conceptual understanding

  • of what an integral is,

  • but not necessarily the fancy tricks.

  • At least at this point, if you're studying.

  • - Absolutely, there's nothing that we go after

  • the fancy tricks.

  • We're not trying to ask trick questions

  • or play any gotcha moments on it.

  • It's really assessment of calculus.

  • And for the students who have been going through

  • these great courses all year,

  • this is a wonderful opportunity to show us

  • everything that you know

  • and get a really great score on the exam.

  • - And what about calculator?

  • I mean, I was doing some of the free response.

  • That first part of the free response,

  • knowing your calculator well helps.

  • - Oh, absolutely.

  • The calculator's a tool,

  • and like any tool, you want to make sure

  • that you're applying it appropriately and strategically,

  • which sometimes means using your calculator,

  • and using it well and correctly,

  • but other times not using your calculator.

  • I mean, even on the free response section

  • where the calculator is being used,

  • we expect students to show their work.

  • If you're taking an integral,

  • we wanna see that you've actually taken that integral.

  • Now, the calculator will do the work of it,

  • but we wanna see the notation that says

  • this is the integral you calculated,

  • and this is the answer you obtained.

  • And then do whatever you will with that answer

  • as required by the question,

  • but good communication through writing,

  • even on the calculator section, is necessary.

  • - And for students taking the BC exam,

  • above and beyond the core differentiation,

  • integration, you know, a lot of what you learn

  • about parametric equations is actually just an extension

  • of what you learn in differentiation, integration.

  • But probably some of the convergence tests

  • are something to become pretty familiar with.

  • - That would be correct, yes.

  • - And in terms of grading of the exam,

  • you know, some people,

  • to get a five or a high,

  • my understanding is you don't need to answer

  • absolutely every question perfectly.

  • - Well, like any test, if you want to do well,

  • you don't have to have perfection on it,

  • and this is a test where students are coming in

  • and it's a three hour timed test,

  • well, a little over three hour timed test,

  • and you know, you can do a lot of really good work

  • and earn a five pretty easily.

  • So I wouldn't tell anyone to go in there worrying

  • about trying to figure out what magical numbers they need

  • to get in order to get a perfect score on the test

  • or to get a five on the test

  • or whatever it is that they're going for.

  • Just go in like you would on any test,

  • do your best on every question,

  • get every point that you can,

  • and hopefully it'll work out fine for you.

  • - What advice would you have for students,

  • especially on the free response

  • where there's multiple sections,

  • and if, you know, on part A they say,

  • what, that, that's,

  • I don't get what that, what,

  • you know, should they skip to the next free,

  • what should they do?

  • - I actually have very common advice on that one

  • and that's to make sure that students are trying

  • every part of a free response question.

  • One of the misconceptions students have

  • is exactly what you said.

  • If you hit part A and you're freaking out a little bit

  • because you don't know what part A is about,

  • that's okay, move on to part B.

  • There are some questions where the answer for part b

  • depends on part A, but for the majority of the questions,

  • they're separate pieces.

  • So part A, part B, part C,

  • if there's a part D,

  • they might all be asking very different things.

  • And if you have trouble even with part C,

  • that doesn't mean the question

  • gets progressively more difficult.

  • Give part D a try.

  • And a lot of the things that we do give points for

  • are good, solid calculus work.

  • So if you can set up a problem,

  • maybe you don't have time to finish it,

  • maybe you make some mistakes along the way,

  • the answer point is only one little point

  • out of the nine.

  • There are other points for the setup

  • and the conceptual understanding of the problem,

  • and a lot of students have good conceptual understanding

  • that they could set up,

  • pick up a point here, pick up a point there,

  • but they panic a little bit,

  • and they move on to another question

  • and never come back.

  • And that's okay if you want to move on to another question,

  • but absolutely I would say,

  • if you're having trouble with part A,

  • that's all right, take a look at part B.

  • - And one thing that I've observed is

  • a lot of these questions, at first when you look at 'em,

  • like oh wow, this looks like some really,

  • you know, super deep thing,

  • but it really is some core basic calculus ideas,

  • and that if you're on the right track,

  • it's actually quite simple.

  • Would you say it's fair if a student finds himself

  • doing a very hairy calculation

  • that they might question whether they need to?

  • - I would go beyond might.

  • They should question what they're doing.

  • If you've done something where you feel like

  • you need to prove a new calculus theorem

  • in order to answer it,

  • something has gone terribly, terribly wrong.

  • And also, if you feel like you need

  • to bring in some sort of mathematics

  • you've never seen before in calculus,

  • as much as I hate to say it, you know, this is calculus.

  • It's limits, it's derivatives, it's integrals.

  • Even though there's a lot of wealth in that one,

  • if you're doing something beyond that,

  • probably something has gone wrong.

  • - Yeah, yeah.

  • Well, thanks.

  • I think, you know,

  • thousands of AP students are gonna really appreciate that.

  • Any other parting words for the coming test?

  • - You know, it's the same thing

  • that I used to tell my students

  • when I was teaching AP Calculus,

  • this is just another test,

  • and the beauty of AP is the teachers have been

  • prepping their students since the beginning of the year.

  • It's one of the few tests

  • where everyone knows what's coming,

  • so when you sit down and you've got free response questions,

  • you've got multiple choice questions,

  • you know, there really shouldn't be any surprises.

  • This is the stuff they've seen all year.

  • They know what to do.

  • Take a moment, take a breath,

  • take a look at the problem,

  • get all the points that you can.

  • Show us that good calculus.

  • - Awesome, and I'll throw in a plug.

  • We have tons of resources for the students as well,

  • and we're gonna have our office hours on Monday.

  • So, super exciting.

  • Thanks a bunch, Ben.

  • - No, thanks for having me.

- So this is Sal Khan, founder of the Khan Academy.

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