Today marks another ‘ending’ to the inaugural, AP Chemistry course that examined the new curriculum for the first time in May of 2014. I say ‘another ending’ since there have been at least two other ‘endings’ up this point. The first ending was when I finished teaching the course, the second ending was when the kids finished the exam, but this ‘final ending’ really represents a complete circle of events that started (for me) back in September 2011 – the release of the first set of AP scores associated with the new course.
There has been much comment, gnashing of teeth and other discourse since the exam and in the wake of College Board releasing information about the distribution of scores. In a nutshell the % cut off for a 5 on the exam was set at 72% (up to perhaps 10% higher than traditionally required in the past), and as a result the number of 4’s and 5’s globally were cut drastically compared to early years.
The real problem with this new distribution is two fold;
- Firstly, the questions on the 2014 were in no way significantly harder or significantly easier than in the past, and
- Secondly, despite the fact this was the first year of a new curriculum, there was nothing in the way that the questions were worded that suggested that they should be answered (or would be graded), in any significant way that was different than in the past.
The first bullet-point is not in any dispute with anyone with any knowledge of the AP chemistry exam over the years, but the second bullet-point is crucially important.
A problem came to light in a recent exchange on the AP Chemistry Community Forum where it was revealed that question 7(d) (below) HAD to have some reference to ‘particles’ in the answer in order to get the point.
It so happens that my draft answer for 7(d) did provide a particulate explanation (and hence scored the points), but this necessity is not at all clear from the way the question is worded; as such it’s totally unacceptable as a required answer, since it holds the students (and teachers) to a standard that they don’t even know exists!
Another, similar problem came to light via my communication with a Table Leader who told me that there was an issue with Q4(c). Apparently that question (below), in his words, ‘REQUIRED either mention of the constant temperature (which was unstated in the problem) or an answer using Le Chatelier (why???)‘.
This simply is not fair. I have no problem with the College Board asking whatever they like, but we cannot have cryptic requirements that are not clear to the students or stated in the questions – that’s simply not on.
Anyway, back to this years scores. What any of these statistics mean is difficult to know with such a small sample, but because of what I have said above about the relative difficulty of this years exams, and with a comparable group of students and the same teacher, I do not think that I should have seen any kind of significant change in the scores – I didn’t. Here’s a breakdown of the last 13 years of my students scores.
I sent in this list of questions earlier this year, they sent back a polite/empty response the day after the exam I believe. I’m not teaching AP chemistry in the future, but the problems get worse as you go back in my opinion. I also think the AP test is the best test there is, but it’s so difficult to communicate with them that it could be much better.
– are units required during the problem solving process and in answers that do not specify to include units?
Your grading schemes say that work is required, what is work? What exactly would you like shown?
– Are students penalized for plugging in moles into an equilibrium expression instead of molarity even if the volumes cancel?
– why is endothermic an acceptable explanation of why a temperature change will decrease. Should not the answer instead point out that the enthalpy of the chemical is increasing therefore the surroundings must lost the energy causing a cooling effect?
2012 Q3 –
the explanation given for part f is not an explanation, it’s just a statement. There should not have been an addition of requiring an explanation of why 1st order plotted 1/concentration vs. time does not result in a linear fashion, but since it did, it should be explained.
2012 Q4 –
isn’t fizzing sound an observation easily made when a carbonate reacts with a strong acid?
2012 Q5 –
your answer does not meet your own criteria for answers. You say in the follow up that an explanation of entropy increase must include a description of what entropy increases are.
question 3 part e – what work would you like for this? It’s addition and subtraction….
2011 Question 5
Why do they specify dipole-dipole for hydrazine when hydrogen bonding is also listed. They are duplicating the intermolecular forces, hydrogen bond is an unusually large dipole force. It should say or, or dipole shouldn’t be listed.
question 5 part e
This is high-level, but acid-base should not be listed as an option as any coordinate covalent bond formation is an acid-base reaction. We don’t know what the reaction mechanism is and it is not unrealistic to assume that this could happen in the reaction. If a student put this answer and justified would they get the point? Would your graders know to look for this?
2011 5 part b
In the grading q+a it says that stating lone pairs does not constitute a justification but you simply state the geometry which bites the same kritik. You really should go back and award points for the lone pair mention as that is a critical connection and is a much better answer than just saying they aren’t in the same plane because it has a shape. How do we know that the writer knows that trigonal pyramidal implies the bond angles that make it impossible to remain a flat molecule?
a. Why is a constant amount of ethanol incorrect? A constant amount of ethanol explains why the pressure does not change quite nicely assuming constant temperature, which is specified.
b. It says that more intense collisions is marked down, if intense is used over more energetic or larger. This seems like it punishes students who do not know physics language for a chemistry concept that they do understand.
c. Why are collisions between gas molecules not indicative of pressure? This implies that the wall is made of something different than that of the gas molecules.
Scott – you DO know that the Scoring Standards released by the College Board do NOT necessarily reflect all answers that would score full credit, right? So for example, the answer to your question about 2012, 4(a)(ii) would most likely be, ‘Yes, that would be indicative of a gas being released and therefore that would be an entirely acceptable, full credit answer as well’!
As for 2011, 3(e), yes, that’s how one finds the voltage so show the numbers being added/subtracted!
On 2011, 6(a) I don’t see your problem – that’s the answer given is it not?
In that light I think that some of your quibbles with grading are a bit different to the ones that I have but are you trying to make a similar point? I’m not quite following your posting of these questions in association with this blog post.
Sorry for not being clear, yes I am in agreement. I have a huge discrepancy between my MC (very very good) and FRQ (slightly above average) relative to the nation and I feel like I am getting marked down for not teaching what wordings/mechanisms of answers get points but I am teaching chemistry well. This year I tried to circumvent this problem by going through and reading the grading analyses posted on AP’s site. The 6a answer I believe was specified as to not receiving credit in the graders analysis but is quite similar to the answer posted.
It seems like the AP has a limited chemistry understanding and when they understand something they try to expect more out of that answer but there isn’t much consistency with this. For some things you have to explain in great particle detail, but on kinetics rate laws just restating the question is usually sufficient.
That makes the curve this year very frustrating because I don’t think the teachers who have not graded exams are aware of how nitpicky they are and so they overestimated the cutoffs and AP seems to have no basis for their curve other than this.