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15 April 2014

AP Physics 1 and 2: What raw score will be necessary to earn a 5? (Update July 2015, see comments)

Okay, that's the question of the year for 2014-15.  For decades, the raw score to AP score conversion on the Physics B exam has been relatively consistent -- in the neighborhood of 65% for a 5, 50% for a 4, 35% for a 3, 25% for a 2.  I've used those cutoffs in my own class on each of my monthly tests.  Sure enough, students who consistently earn what I call "5s" on my in-class tests tend to earn 5s on the actual AP exam.  

But what's going to happen on the new AP Physics 1 exam?  The style and structure of the Physics 1 exam is substantially different from that of the Physics B exam.  We have no word from anyone at ETS or the College Board about how the score cutoffs might look.   

The actual score cutoffs will be set by a complex data mining process involving statistical wizards at ETS and a committee -- not the test development committee, a different committee -- of high school and college physics teachers.  A College Board representative described the process briefly to the consultants at our weekend meeting.  I didn't quite follow all the details.  Suffice it to say, it's a statistically rigorous process, but one that can't be gamed or anticipated.  We will not know anything real until the summer of 2015, after the first exam adminstration.

So how should an AP Physics 1 teacher set expectations in class this year?  That's going to require a significant amount of guesswork.  We teachers have only a few data points to guide us.  

The first set of data is the previous years' physics B and C exams.  The physics B exam changed significantly in its emphasis in the mid 1990s; yet the cutoff for a 5 remained around 60-65%.  Physics C contains two completely different courses and exams.  Physics C mechanics cutoffs in the 1980s and 1990s were about 10% higher than the E&M cutoffs; since the mechanics exam added more experimental and conceptual questions, and since it placed more emphasis on calculus-based problems in the free response problems, that gap has lowered to essentially nothing in the last two released exams.  On either exam, you now need in the neighborhood of 53-58% to earn a 5.

The AP Physics exams have changed gradually and organically through the years, but the redesign to the new AP Physics 1 and 2 courses will be seismic and unprecedented. 

Um, wait... not unprecedented.  The College Board did a similar redesign of the AP Biology course for the 2013 exam; and of the AP Chemistry course for the 2014 exam.  The 2013 AP Bio exam has been administered and scored.  While biology is a completely different animal from physics, perhaps we can draw some lessons in how the cutoff scores changed from 2012 to 2013.

In 2012 (before the redesign), the score cutoffs for AP Bio were:
5 73%
4 63%
3 55%
2 46%

In 2013 (on the redesigned test), the score cutoffs for AP Bio were:
5 77%
4 62%
3 45%
2 25%

Now that I've seen these, I better understand what bio teachers have told me about the new test.  They say (and the College Board confirms) that far fewer students earned 5s on the new exam, far fewer students earned 1s, but more people scored in the middle of the distribution.  That could be a result of the new style and content on the exam, but it could also -- and in my mind, more likely -- merely be a consequence of the higher cutoff score for a 5 and the way, way lower cutoff score for a 2.  We'll see in August whether the AP Chemistry redesign produces a similar scrunching of the bell curve.

To summarize:  Physics B cutoffs have been consistent over decades.  Physics C cutoffs recently have been consistently a bit lower than physics B cutoffs.  The redesigned AP Bio test raised a wee bit the cutoff for a 5, but substantially lowered the cutoff for a 2.

What should you do?  What am I going to do?

Not sure yet.  My gut is still telling me to stick to my current cutoffs for the first year, because these will be close enough.  I do like using cutoff scores that are easy for students to remember: 65%, 50%, 35%, and 25% are nice round numbers. I'll let you know if I end up changing my approach.  

25 comments:

  1. Update as of July 2015: Trevor Packer released an official letter to AP Physics teachers on the CB's teacher community. It included the raw score cutoffs for 2015. They are:

    Physics 1:
    5 71%
    4 55%
    3 41%
    2 26%

    Physics 2:
    5 73%
    4 61%
    3 42%
    2 23%

    These are, obviously, official for 2015 only. I'll post soon with further commentary.

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    1. Well, here I am in 2016. Do I dare extrapolate to the May exam, using these as a rough guide? I can't see to dig up anything better anywhere.

      Jeff at JLHS

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    2. So, my question is do I dare use these as a rough guideline for the upcoming exam? I mean, it isn't as if I have anything else to go with.

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    3. Jeffrey, as you point out, there's not much else to go with... so that's what I'd use.

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  2. Hi, I shared your percentage cutoffs in the original post in with my school's AP Bio teacher. Now the AP Chem teacher is wondering where hers can be found? I've been clicking through reports on AP Central but can't seem to find it... any links?

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  3. I'm not sure. I got the physics cutoffs from a special letter from Trevor Packer to AP Physics teachers, and then I had to do some calculation to get the percent cutoffs. I used to get these from previously released complete exams, when they published not only the entire exam and scoring rubric but also the raw scores necessary for each grade. I don't think that's happened for any of the redesigned science exams yet.

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  4. Is there any polite way one might ask for them to do that? I'd be happy to ask, but have no idea who I might speak with.

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  5. And, yeah, I'm certainly going to use the available cut-offs. Better a candle than the darkness, I say.

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  6. On a related note, I have been doing daily quizzes and monthly tests, allowing my kis to correct their errors, refunding 1/2 the missing points, and then using the so-called "Texas curve." Am I being too generous here? My feeling is that I don't want a student to get an A in the course and then get a 1 or 2 on the Exam, but I also don't want them bringing home C and D grades, either. For reference, my students currently have mostly B grades. These are based largely on the quizzes and exams, with a strong lab component, as we spend probably 30% of our time "doing." Looking at their raw scores on the quizzes and tests, they range in the 6 of 10 to 8 of 10, on a diet of MCQs and FRQs from that huge Workbook that everyone seems to be using (or am I lone here?), so that seems to line up reasonably well with some kind of 3 - 5 grade on the actual Exam. As you can probably infer from my post, I spend a lot of time agonizing over this. It's only my 4th year teaching AP, so I'm still really new at it. Lots of room for improvement here!

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    1. That sure sounds reasonable to me... and it sounds like you DON'T have A students getting 1s and 2s on authentic AP items. You're doing it right. If your grades are too high or too low based on this year's exam performance, you can always correct a bit in next year's class. We're *all* new to this Physics 1 thing.

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  7. Curious what a "Texas curve" is? I'm finding the same kinds of issues with top kids and C's and D's. Doing something similar with corrections for part marks returned. Seems to work? I like that as opposed to a straight curve since they have to demonstrate understanding. Where it backfires is if a kid chooses not to do it. Have been agonizing as well. 1st year AP teacher coming out of IB, which is similar in its marks concern, but what my old school did to mitigate it was give them IB 1-7 grades on their report cards instead of the raw percentage.

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    1. Hi Catherine,
      Sorry, I've been busy with "self-assessment" work, Yuk! I learned it from another much more long-time AP teacher when I started. I've never been big on curving, but, like you, I don't want hard-working kids with Ds. So here's an example. ALL my Daily Quizzes (DQs in my Gradebook) are either 5 to 8 MCQs or one FRQ. So, let's say a student gets 4 of 8. I count every DQ as 10 points, to keep things simple. So 4/8 = 0.5. Then take the SQRT of 0.5 and that's .707, so it goes into the book as 7.1 out of 10.

      The issue I have had this year is that kids began scoring really low, so I was awarding 1/2 credit for corrections, which I began doing after reading this Blog, but then I started using the curve as well. I found that this was over-inflating the letter grades when I tried to correlate them with AP grades. In other words, a kid with a raw score of 50% would do well in AP B, but not really in AP1. So I have decided to just go with the 1/2 credit thing. This way, they are getting more like high C low B, but that's really better, because they are grade-motivated and will work harder to do better. In any case, I will never go back to using both; that was a mistake. And I agree; the error correction is a great learning exercise. I even found an article in an old issue of "the Physics Teacher" that presented evidence supporting doing it.

      As far as kids not doing the corrections, it's a college course with college consequences. Lack of effort isn't something I willingly deal with. I grade pretty much everything college style: late = 0 and so on. I find that they moan about it the first time it happens and then it doesn't happen again. Nothing like a zero on a lab report to wake them up. Right now I have everyone B- or better, 2 weeks into the 3rd Quarter. Monthly test tomorrow and An Inquiry (SHM) due Wednesday, with that rubric they detest! I'll see how it all looks Friday.

      It sounds to me like you have a good handle on it all; just remember, there's no shame in saying "oh s**t this isn't working" and then doing something different. I'm still a recovering idiot, learning as I go.

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  8. Catherine, if they don't do the corrections, they don't deserve the grade bump. It's actually an easier sell to parents to give a bad grade for someone who doesn't do the easy, collaborative corrections work -- see this post http://jacobsphysics.blogspot.com/2011/10/fact-based-criticism-test-corrections.html

    Don't know what a "Texas Curve" is offhand... Jeffrey?

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    1. Sorry ... I have been working as an environmental consultant and haven't been online in a bit ... it's simple. Take the raw decimal grade ... say it's .81. Then take the SQRT, so it becomes a .90. It's regressive, in that a lower score gets a bigger bump than a higher one. I have used it ... half-heartedly ... for a while, but honestly, I'm happier to go with the 50% restored credit for corrections and let the kids deal with it. This year I had only 6 students. My two B+/A- kids got a 3 and a 5, my three C kids got a 4, a 2, and a 1. The student with the 2 was going online for answers ... I could tell ... and honestly, I'm almost certain my B+ student carried the one who got the 1. I feel like I let them down somehow an am going to try a somewhat different approach this year. We will begin right away with succinct written explanations!

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  9. Just to weigh in on the curve bit. I curve my tests for AP. (I don't have data to support this assertion, but according to student comments and responses I appear to be in the minority as an AP teacher at my school who curves their tests.) The reasons I curve are because the AP scale is curved and I want students to be appropriately rewarded for their performance (a 75% on a difficult test is *good*). The students seem to appreciate the curve and understand why it is there (we've repeatedly discussed the break points from last year's exam).

    After the first test, I briefly researched different types of curves, including pros and cons. Given my goals, I settled on a modified power curve: (100^(1-a))*(x^a) where 0 < a < 1 and x is the score as a percent (for example, "58" for a 58%). Corrections are all but required and students receive half of the lost points back. (Not turning in corrections may mean that I use their original, raw score - which no one truly wants.)

    I use the corrected score as my base (x) in the above formula. I then add or subtract a few points based on their original score (for example, anyone with 70% or higher gets +5, those with 20% or lower get -4, etc. - it's a tiered range of comparatively small +'s and -'s). The modification of the power curved values is because a power curve intrinsically favors the low end and I want both ends (high and low) to be appropriate (if the top scores are 75%, they deserve a solid A). Thus far, the a parameter has fluctuated in the range of 0.75 to 0.8. I try very hard not to give F's - if a student is honestly trying, I won't fail them. The contrary is also true - if they're not working hard or putting in much effort, I won't give them much. It's a quid pro quo (so to speak) and they have to uphold their end of the bargain.

    The Excel spreadsheet that cost me one Sunday's time and effort (well spent says I) is a g-dsend. I put in the raw scores and it spits out final grade values along with a graph showing me the final distribution across letter grades. I then play with the a value and the additional points until it looks and "feels" right. I often pick a test score and make sure it hits the appropriate mark (for example, a 35% usually is a C, though it could go higher or lower in view of the overall trend).

    I'm quite pleased with how it's working out. The students' responses have been positive and encouraging. They have to learn from their mistakes and in return they receive a grade that won't kill them and (hopefully) accurately reflects their progress. I plan on using it through the rest of the year and probably next year (unless I find something better).

    If anyone wants the Excel spreadsheet/workbook, let me know. I still have to tweak the code a bit (I got comments from a friend who knows Excel better than I do), but I'm happy to share the framework.

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    1. Hey, Alan! How are you? You work too hard, LOL. I'm working on the Goruck model: "Underpromise, Overdeliver," myself. I'll let 'em have the slightly lower grades now in exchange for the higher AP grades later ... well, that's the plan, anyway.

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    2. Hi Alan, Could you share the spreadsheet? Thanks!!!

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    3. Alan, I'd like to have a copy of that spreadsheet, too! Thanks!

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    4. Sorry for the delay. I just finished reworking the entire spreadsheet. It now has documentation embedded and I got rid of the "corrections = half points back" piece since I was requiring corrections for the curve (no need for the extra step of half points back).

      Link: https://drive.google.com/file/d/0B0a_oG6FP86BUUNTV0NiaWdGTnc/view?usp=sharing

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  10. My daughter is going to take an AP Physics this May. She is self- learning. May I know where I can get a test sample to estimate her raw score? Thank you.

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  11. I'd suggest the 5 Steps to a 5: AP Physics 1 book. It has two authentic sample tests with scoring estimates. The College Board provides practice tests, but these are available only to AP teachers. Beware of sample tests produced by textbook or prep books. Good luck!

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  12. Any speculation as to what the cutoff will be this year for a 5??
    To be honest, hoping for a 65% or so

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  13. I really have no clue, Anon... the cutoff is determined statistically. The goal is that the level of achievement represented by a 5 is identical year to year. There's no thought of what that means in terms of % correct, or of % of population getting each score.

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  14. Just took it. Failed. Hope the curve looks like this: 2-15%, 3- 30%, 4- 45%, 5- 60%

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  15. @Anon When my teacher gave us a College Board practice test, I got the lowest score possible for a 5, and it was a 64%. Hopefully the cutoff won't be as high as a 71% this year...

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