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Author Topic: students who don't recognize the answer  (Read 8618 times)
ptarmigan
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« on: April 26, 2012, 8:54:33 pm »

In terms of partial credit, how do you guys grade questions where the student has the right answer but doesn't recognize it?

I gave a quiz today where one question was to convert an equation (x^2 + y^2 = 100) to polar coordinates. I had numerous students write the answer (r = 10) as one of the first two or three lines, but then proceed to do a bunch of other work (often wrong), followed eventually by a completely different answer circled, often an ordered pair, which is not only wrong but the wrong kind of answer entirely.

On the one hand, I feel like giving them some partial credit for being able to get the right answer, even though they followed it by doing wrong things. On the other hand, I feel like not even knowing what type of answer is called for is actually worse than simply not being able to compute the answer. It shows that you don't even know what's going on, which is worse than not having a particular technique.

What say you, o wise ones?
« Last Edit: April 26, 2012, 8:54:54 pm by ptarmigan » Logged

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frogfactory
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« Reply #1 on: April 26, 2012, 9:23:03 pm »

This is why I specifically write on my exams something to the effect that, where multiple answers are written in the available space, only the circled answer or the bottom-right-most answer will be considered for grading, *even* if the correct answer is also written elsewhere in the space.

Whether it's worth partial credit in this case, though, I have no idea, since my exam questions generally don't involve showing your working.
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blackadder
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« Reply #2 on: April 26, 2012, 9:26:14 pm »

Is part of the question requirement to show the steps? I would give partial credit if that is the case. Analogy: Nursing students demonstrate the steps to a sterile dressing change. They get the dressing changed but fail to wash their hands first. The end product was fine, the steps were messed up. If they don't know the steps, then eventually there will be a problem.
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prof_cj
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« Reply #3 on: April 27, 2012, 10:34:01 am »

If the intent was to not only get a correct answer but to illustrate the correct steps in order to get that answer, then I'd only give partial credit at the most.

Is this an intro-esque course? It's not a perfect comparison, but in the intro Eng. classes I teach, multi-step writing assignments need every step handed in for me to assign a grade, because the steps are more important/just as important than the end result writing assignment.
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ptarmigan
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« Reply #4 on: April 27, 2012, 3:27:46 pm »

It seems like most of you are replying about a situation in which the student has the correct answer but the steps are wrong. I'm talking about a situation in which the student got the correct answer almost immediately but (apparently) saw the answer as the first step in a long chain of reasoning (all or most of the remainder of which was wrong) leading to a final answer that is nonsense. A somewhat analogous situation in words might be

Q. Who is Nicolas Sarkozy?

A.

(the president of France?)

Sarkozy is a term often used for the prime minister, because he is thought to be "kozy" with Merkel, the vice chancellor of the Weimar Republic of what is now known as Germany. In short it is a derogatory term that shouldn't be used in polite company.
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conjugate
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« Reply #5 on: April 27, 2012, 6:22:10 pm »

Circle the right answer (so they can't circle it later and claim you "didn't see it") and give them, say, 1 or 2 points (depending on the point value of the problem).

I have a similar difficulty; I asked a test question about whether the sequence 2^{3-n} converges.  A few students wrote, "Yes, it converges because it is a geometric series, and the ratio r satisfies |r| = ½ < 1."  They should know that it is in fact not a geometric series but a sequence.  However, they also know that the key point is that the ratio is less than one in absolute value, and they know that this affects convergence.  So I give them half the points (which may be too generous).

I'm happy to say that I give no points at all to those few who still try to use the nth-term test to prove convergence.
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zookers
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« Reply #6 on: April 30, 2012, 11:49:57 pm »

I used to be the purveyor of partial credit.  When I got my first teaching position, I figured "I know what they *meant*!", and believed it to be too petty to take points off for these kinds of problems.

Nowadays, I feel exactly the opposite.  If the students come up with a correct answer and back it up with nonsense, they have obviously missed the point.  I'm also on the fence with students who "throw stuff at the wall" in a response, since it's obvious they're hoping that somewhere among their many words will be a few right answers.

When confronted with the usual "why didn't I get partial credit for this?", I honestly tell them I can't justify grading their answer correct (or even partially correct).
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fiona
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« Reply #7 on: May 01, 2012, 12:09:47 am »

It's very hard to read students' minds or to calculate random stuff thrown at the wall.

I would go for, in future, putting in the instructions that only the right answer will count. And that the right answer has to be circled, underlined, whatever.

Anyone not following directions doesn't get credit, which is a good life lesson that most of our students need.

But I'm in the humanities, so situations like the OP's don't really arise.

The Fiona
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traductio
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« Reply #8 on: May 01, 2012, 12:30:53 am »

It seems like most of you are replying about a situation in which the student has the correct answer but the steps are wrong. I'm talking about a situation in which the student got the correct answer almost immediately but (apparently) saw the answer as the first step in a long chain of reasoning (all or most of the remainder of which was wrong) leading to a final answer that is nonsense. A somewhat analogous situation in words might be

Q. Who is Nicolas Sarkozy?

A.

(the president of France?)

Sarkozy is a term often used for the prime minister, because he is thought to be "kozy" with Merkel, the vice chancellor of the Weimar Republic of what is now known as Germany. In short it is a derogatory term that shouldn't be used in polite company.

I don't know why, but this is the funniest thing I have read all week!
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mountainguy
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« Reply #9 on: May 01, 2012, 9:18:27 am »

But I'm in the humanities, so situations like the OP's don't really arise.

Actually, when I gave identification or short answer questions on exams at PepsiU, I would get "Sarkozy"-type answers on a regular basis. The students think they're hedging their bets. I now include a disclaimer on short answer questions that factually incorrect information will be marked wrong.
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mended_drum
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« Reply #10 on: May 01, 2012, 9:34:55 am »

But I'm in the humanities, so situations like the OP's don't really arise.

Actually, when I gave identification or short answer questions on exams at PepsiU, I would get "Sarkozy"-type answers on a regular basis. The students think they're hedging their bets. I now include a disclaimer on short answer questions that factually incorrect information will be marked wrong.

And on a quiz with a simple question:  "Who is the murderer in this story?" there is always at least one student who responds with two answers, hoping one is correct.  So I tell my students that I only accept the first answer; they can't just make a list.
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ptarmigan
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« Reply #11 on: May 01, 2012, 9:55:10 am »

Thanks, Traductio. I had a weirdly large amount of fun writing it.
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wittgenstein
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« Reply #12 on: May 01, 2012, 10:42:40 am »

I teach Calculus II and III. I have developed a technique where all problems are worth 5 points. This makes partial credit easier.

-1 if you make an arithmetic error
-2 if you used the correct technique but didn't make it all the way to the end.
-3 if you made an H.A.M. (horrible algebra mistake, like thinking (x + y)^2 = x^2 + y^2
-4 if you were in the room while a test was taking place and wrote something down.

So, in the case of the problem you are talking about, I would grade it -2 -- not confident enough to stop at the right answer.
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macadamia
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« Reply #13 on: May 01, 2012, 2:08:26 pm »

It is absolutely legitimate to take off lots of points for adding nonsense to a correct stuff (and no, horrible algebra mistakes are not the most horrible things by far).

On the other hand, one should not make to sweeping conclusions on the knowledge of the nonsense perpetrators. It is amazing what kind of nonsense one can write down while having the correct idea in a slightly confused and distracted head.

But I have to say that I have found that math grades are quite robust with respect to type of question asked. We tried asking one "easy" question at the beginning of the test. The students who could answer the easy question were the same ones that could answer the difficult one necessitating lots of preparation.
« Last Edit: May 01, 2012, 2:10:14 pm by macadamia » Logged

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nucleo
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« Reply #14 on: May 03, 2012, 7:29:14 pm »

And on a quiz with a simple question:  "Who is the murderer in this story?" there is always at least one student who responds with two answers, hoping one is correct.  So I tell my students that I only accept the first answer; they can't just make a list.
Wow, you accept the first answer?  I mark a zero on the whole thing if the question clearly has N answers and someone puts greater than N things.  I explain to my students that answering, "What are the three colors in the American flag?", with "Red, Orange, Yellow, Green, Blue, Purple, Black, and White" tells me that the student has no clue and is hoping to get lucky whereas "Red, white, and dang, I forgot" is a pretty good answer.

The way I'd mark that one is that for each missing or extra answer, I take off half a point until there are no points left.  So "Red, white, and dang, I forgot" and "Red, white, blue, and green" would both lose half a point, while "Red, white, and green" would lose the full point (and these types of questions are typically worth one mark for me).

Where I see this most frequently is when I ask students to expand, say, (x+3)(x^2-3), for two points.  Almost all students will multiply this out correctly, but the weaker students will then try to factor it.  I take off one for the attempt to factor, and then point out in class that if they'd done it correctly, they should get the original answer.  However, the students who try to factor it again are invariably weak enough that they don't even get close to the original answer.  Then, meanie that I am, I'll take off the remaining point for whatever algebraic atrocity they committed in screwing up the factoring.
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