OFFICIAL 2012 AP Computer Science A Thread

<p>@nj lol yeah that’s what I wrote on the AP Exam, I just confused myself right now though lol. So if I used spaces.length, it would be full credit, right?</p>

<p>@killerskullz I believe so.</p>

<p>@Divad57 From what I’ve seen on other test’s rubrics the mistake is typically a minor deduction - however, if it voids the entire solution then I believe they treat it more seriously. I originally wrote my solution with an iterator, and had to cross it out because I realized it was an array :/</p>

<p>What do you mean by taking it more seriously? Like a 0 for the question? My problem is that I allowed myself to insert a horse into the proper place in the array, and then removed the horse from the original position. I basically changed the size of the array by one temporarily which is obviously not allowed for an array.</p>

<p>I thought that the test was not that bad :P</p>

<p>However I thought that there was way too much tracing on the multiple choice section :P</p>

<p>Repeating standard disclaimers: for questions like “how many points will this error cost”, I’m offering my own opinions only. I haven’t seen the official rubrics, so my opinions are mine alone. </p>

<p>@ameliab12: failing to account for a call to restore() before a call to act() feels like a 1-point deduction to me … maybe 1.5 points, depending on how much else is going on. (But that’s just a guess.)</p>

<p>Efficiency (in terms of running time of the code) shouldn’t matter in scoring the problem. If it works, it’s eligible for full credit, regardless of how long it takes.</p>

<p>Negative numbers for pixelCount doesn’t seem like more than a 1 point deduction — there are plenty of other issues that have to be scored in that problem (loop bounds, row-major order, etc.).</p>

<p>@killerskullz and @njdevs14: confusing .length (for arrays) and .size() (for ArrayLists) is a non-penalized error. It happens all the time, and we overlook it.</p>

<p>@Divad57: confusing arraylists for arrays could be a significant error. If it was only confusing the accessors ("[]" and “get()”), it would only be a half-point error. But you probably confused the mutators (e.g. calling add() on an array), and that’s more significant. Probably you’ll end up losing many of the points dealing with whether you make the required changes to the array. There’s still some points available for you to earn: making the correct decisions as to how to make the modification, for example. But this is a fundamental issue, and it may be scored accordingly.</p>

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<p>Common misconception. In Java, subclasses do NOT inherit superclass constructors. They only inherit instance methods of the parent which you can override if you want.</p>

<p>The confusion comes from the Java rule that any subclass constructor you create MUST call one of the parent’s constructors as the first line of the ctor body. In fact if you leave this out, Java will implicitly call super(); in any ctor you write in your subclass.</p>

<p>I thought it was pretty easy and kind of what I expected. I mean, you knew you were going to have to override some things, and the new method was pretty straightforward.</p>

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<p>What made it weird was that it was the first ever Bug subclass problem on the free response. If you studied the past released free response tests, all previous questions were related to extending the Critter class. (well except for the Gridchecker one).</p>

<p>As far as the specific question, it was weird that you didn’t have to use the inherited move(), turn(), canMove() like BoxBug. So the RetroBug was really just testing if students knew how to save the state of the bug so that it knew what to do in the restore method.</p>

<p>Still f you had a decent instructor, they would have assigned you various Bug subclass projects, and then various Critter subclass projects, and in those assignments, have you do partial overrides and full overrides of act()/processActors() etc…</p>

<p>In general, I tell my students to always override act() when subclassing Bug, never override act() when subclassing Critter.</p>

<p>Good thing the free response was the first bug extension one ever… I never learned critter. Guess I got really lucky ehh</p>

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<p>Not really, if you didn’t know Critter then you probably missed the multiple choice questions on Critter.</p>

<p>So, the multiple choice was definitely the harder part of the test… do you guys remember getting like 4 or 5 E’s in a row in the first column of the test? It’s bothering me, and although elsewhere on this thread a couple of people said they did, I just want to know if any more people did.</p>

<p>@ZeldaMaster123</p>

<p>There were a good amount of E’s in a row many people at my school got that. I think most of them are correct. I hate how the MC section tried to mess with our head like that.</p>

<p>Edit: I hope the curve will be nice since this was the hardest test I have taken compared to the practice tests</p>

<p>@youngster9</p>

<p>Well, thanks, I feel a lot more comfortable, considering that many people got that. And yes, I also despise how the college board messed with our minds</p>

<p>Hey guys, for the retrobug question on the FR, I messed up while writing the code in the given answer space, so I stapled a white paper with my rewritten code onto the same page in the answer booklet. My proctor specifically told me that I could do this, but I felt like she was inexperienced. Did any of you guys do this, and do you know if this is allowed?</p>

<p>I can say that, yes, stapling paper into the test booklet is allowed. As long as you crossed out the solution in the booklet itself, the reader should see the stapled page and grade it as a “normal” response. (We don’t see it frequently, but we do see it.)</p>

<p>@jkhuggins
I know that it’s been a long time, but I was wondering, how did the scoring go? Did students perform better on the MC or FR? On the FR, how did most students perform on Q2? And also, do you mind telling me what the curve was for this year? thanks</p>

<p>I’ll give you what information I have, but what I have is very limited. </p>

<p>At the reading, we don’t get to see the results of the MC portion. Also, the overall curve isn’t set until a couple of weeks after the reading, once ETS gets all the numbers and can do all of their statistical analysis on them, so I don’t know how the curve was set. “All” we do is score the FRQs.</p>

<p>I didn’t score Q2, so I can’t comment much on that question. I recall hearing that overall performance on Q2 was about as usual (which for most questions is around 4.5/9) — but those were unofficial numbers, and my memory ain’t the best either. There certainly wasn’t anything remarkable about the scoring on that problem — there were good scores, bad scores, and lots of scores in-between, which is what ETS likes to see. </p>

<p>Probably we at the reading were the most pleased about the overall number of exams … the unofficial total was just over 26K exams, which I think is the most ever for APCS.</p>

<p>I just got my online class results back today for <a href=“http://www.hscompsci.com%5B/url%5D”>www.hscompsci.com</a>. My student’s average score was a 4.5 last year, but it’s a 4.0 now. Interesting too because I spent more time on algorithms than I did last year, and the MC really focused on array looping.</p>

<p>I have to take that average with a grain of salt because it could be just my students, but my hypothesis is that the curve is not as generous as it was last year.</p>

<p>All teachers will know more in the next couple of weeks as the overall averages for APCS will be released.</p>

<p>There was no doubt that the multiple choice section was much more difficult than last years, so will be interesting to see the scoring breakdowns. I’ll post back when I get these.</p>

<p>hey i just received my scores yesterday and I’m wondering what other people got if you got the letter or called to find out. I got a 5 as a sophomore so i’m really excited about that. </p>

<p>EDIT: sorry just found a different thread for this</p>