Kevin Drum reports receiving an email from a professor of physics denouncing the Advanced Placement test in Physics:
It is the very apotheosis of “a mile wide and an inch deep.” They cover everything in the mighty Giancoli tome that sits unread on my bookshelf, all 1500 pages of it. They have seen not only Newtonian mechanics but also optics, sound, electromagnetic theory, Maxwell’s equations, special relativity, quantum mechanics and even AC circuits. They don’t understand any of it, but they’ve seen it all. They come into my class thinking, by and large, that objects move due to the force of their motion and cease moving when that force has all been used up; that tables do not prevent things from falling by exerting a force but by simply being in the way, blocking the natural motion; that when a tossed coin reaches the top of its flight, the force of gravity and the force of its motion are balanced; that opposite charges are attracted magnetically; and I could rant on for a while.
Kevin asks:
Anyway, this makes me curious. I have lots of readers who teach at the high school and college level and I’m wondering what they think about this. Are AP tests (and AP classes) all they’re cracked up to be? Or are there lots of you who grit your teeth but secretly agree with my correspondent? And is this just a physics thing, or do history and lit teachers have the same complaint?
The comments are remarkably civil for Calpundit Monthly, but I’m going to respond here anyway (after the cut).
First of all, there are two different versions of the Physics AP test. One of them (I believe it’s “Physics B,” but I’m too lazy to check) is the sort of giant survey course that Professor Camp complains about, using an algebra-based book with all the problems that entails. (I’ve used the textbook he mentions, and I wasn’t terribly impressed.) The other version of the test (“Physics C”) is a calculus-based course that sticks to mechanics and E&M.
In my department, we used to allow students to test out of the first course of the introductory sequence with a 4/5 on the AP Physics C, and out of the first two courses with a 5/5. I think we may have let them out of one course for a 5/5 on the Physics B test, but I’m not even sure of that. I know that 4/5 on the Physics B test wasn’t worth anything. We’ve subsequently revised the curriculum to put some modern physics topics into the intro sequence, so these days all that AP scores get students is admission to the Honors section, which is being taught using a radically different approach.
My limited experience with students who got credit from their scores on the AP Physics C test is that they’re really about as well prepared as any of the students who come out of the intro classes. The sample size in this case is somewhere on the short side of 5, though, so I wouldn’t attempt to draw any conclusions from it. I only know one student who took the Physics B test, so I can’t say much about that. (“Know” in this case means “Know for sure that they took the test and got a good score.” I don’t see the high school transcripts of all of my students, so I’ve probably dealt with several AP graduates without knowing it.)
As for the specific misconceptions Prof. Camp complains about, that has nothing to do with the AP. The sorts of misconceptions he lists are the kinds of things tested by the conceptual diagnostic tests I talked about before moving to ScienceBlogs— I recognize “tables do not prevent things from falling by exerting a force but by simply being in the way” as a wrong answer from one of those tests, and my colleagues and I have chuckled over that one a few times. The thing is, most students leave college physics holding a few of those same misconceptions.
The average score on one of those conceptual pre-tests is something like 10/30, and the post-test scores for a typical lecture class only go up to about 15/30. A really first-rate “active learning” class can boost the average to something like 22/30. My students come in scoring a little better than the national average, and they leave doing a little better than the average for a traditional lecture course, but I still have students on the post-test thinking that objects move because of the force of their motion. (Of course, I also have at least one student a term who will say that the speed of light emitted by a moving object is something other than c. On multiple tests, even.)
This is hard stuff to learn, and really hard stuff to teach. I’m not in the least surprised that students leave high school AP classes with some serious gaps in their knowledge. Most students leave their college classes with some serious gaps in their knowledge, and they think less of us to boot.
You’re pretty much right-on, Chad. The problem of AP is indistinguishable from the problem of what/how we teach anyway.
I’ve had a few students AP test out of Physics I, and I can’t say they’re terribly different from those who took it in college. The sample size is too small to draw real conclusions. If anything, the greater problem in my experience is the community college transfer.
Then again, I’m teaching one of those “mile wide, inch deep” courses. The only intro class we have is calc-based, and the primary audience is pre-med. Sadly, I need to cover what’s going to be included in the MCAT which, at least according to their very helpful guidelines, is everything.
I find I have to cut some topics out entirely, or give only the briefest coverage. That’s not a problem.
Topics I cut out entirely: gravity (although I cover Newton in parallel with Coulomb), Relativity (my favorite, but I cannot justify it)*, AC circuits (no engineers in my class…and don’t they get that in their circuits class anyway?)
Topics I cover briefly: geometric optics (frankly I need to develop some good labs that take it out of lecture completely), wave optics beyond the most basic examples.
Topics I include only if time permits: modern physics beyond basic quantization/atomic physics.
I have started using Serway/Jewett’s “Principles”, which is one of the few calc-based books for pre-meds. For the most part the coverage is reasonable. I used to use Hecht, but its popularity has waned. (Fall 2001: “This book is so easy to understand!” Fall 2004: “This book is absolutely impossible to understand!”)
*For the record, I had included gravity and relativity in my syllabus but dropped them when hurricane Wilma closed us for over a week. Right now I’m not sure I would put them back in next year.
Oh, brother, have you touched on one of my sensitive spots! I have taught AP Physics – C for 21 years, and been an AP grader, and have a lot to say about the AP program, both pro and con.
First of all, you are correct. There are two levels of the AP test. The B test is the murderous survey course the professor bemoans; it uses only trig. The C test covers mechanics and E&M only, with calculus. I have only taught the C-level course, because our school has always favored “less is more.” I cannot see how any teacher can cover an entire trig-based physics text in nine months, even with additional contact time. And if he/she does, I cannot fathom what the students get out of it. I wonder about the C-level program, too, even though we make the AP course a second-year course.
My stint as an AP grader was eye-opening to say the least. As it turns out, many public schools, in an effort to claim they have provided upper-level courses to their students, require (yes, require) students to (a) take an AP Physics course and (b) sit for the exam, regardless of their skills, talents or preparation. The result is a lot of blank papers, helpless flailing around solutions by some kids, and the occasional flash of insight. The ones who get 4’s and 5’s generally know the material pretty well. That is, they can solve the problems and answer MC questions.
Whether they understand the underlying concepts is a different story. The AP program does not stress or measure students’ understanding the conceptual underpinnings of all those equations and laws. Some teachers (as I do) attempt to begin with the concepts first, but the rapid pace of an AP course usually means presentation centers around the mathematical aspects. You have to teach to the test, a consequence of the program that I have never really been comfortable with.
Recognizing that high school students might be getting the content, but not the lab experience, the College Board began a few years ago to include free-answer mechanics problems involving interpretation and manipulation of experimental data. No particular experiments have been mandated as yet, but the questions presume students have performed typical mechanics labs. The rest of the free-answer questions focus on multiple-concept “killer” problems, you know, the three-star ones at the end of the textbook chapters.
The problem with physics at the high school level is not the kind of course, but the frequency of the instruction. I use learning a foreign language as an analogy with my students. Learning physics, or any science, really well requires more than one year, more than one course. Would you expect a graduate of Spanish I to be able to read Don Quijote in the original language, or to be able to write a short story in the target language? Yet we expect kids who take one or two years of physics to be as “fluent” as the professors in college.
I have taught students from the former Soviet republics. There, they had instruction and exposure to chem, phys, bio and algebra/geometry all through the so-called middle school years, a little bit each time. These kids ran rings around ours, because of the depth of their familiarity with the basics, like inertia, the normal force, acceleration, etc.
For high schools, the AP program is a convenient way to demonstrate they offer tough classes to kids (and parents) who want them. Our school has discussed ditching the AP program in all of our subjects, but we have always decided against it. We are a private school, and competition for students is tight. We can’t quit the AP program without jeopardizing losing those top students to other schools, regardless of what high-level courses we offer in their place. So, circumstances seem to dictate keeping AP and dealing with the limitations of the program.
One problem is the number of contact hours. To fit in labs, lectures, problem sessions and discussion for 20 chapters of content, some schools have the luxury of scheduling double periods of AP science. Others make do with one period a day, and meeting students before or after school. Still others try not to waste any time if possible. I’m in the third category, although once upon a time, I belonged to the first. Don’t get me started on why the scheduling changed.
Beginning this year, the College Board is going to have schools validate their AP offerings, to impose some quality control on the country’s only national curriculum. Those schools that are not toeing the line will no longer be able to use the trademarked term, “Advanced Placement,” in their catalogs.
I don’t expect the change will improve matters in Prof. Camp’s lecture hall, though. We really need to start teaching science a lot better in the earlier grades. To do that well, however, you need more teachers, a topic I have blogged about on my site here and here.
I took a lot of AP courses in my last two years in high school (1985-87), in math and the sciences and humanities, and was able to test out of several introductory-level college courses as a result. My experience from looking at the course materials and talking to students in the college courses was that I generally ended up better grounded in the subjects in question than they did.
Part of the reason may have been that the high-school versions of the courses were treated as advanced material for particularly motivated students, and therefore were taught with high expectations of the students, whereas the college versions were considered dumbed-down gut courses for first-years fulfilling their obligatory distribution requirements and were treated as such.
But I went to an unusual magnet school my last year and had a lot of superb teachers; I doubt that the tests themselves really had a lot to do with it. My sister took AP physics at another school a few years later, and reported that the teacher had a lot of trouble reconciling what she wanted to do with the curriculum with the need to teach to the test.
Frankly, I abhore these classes/tests.
When I was in high school I took Physics (with calc), AP Physics (C), Modern Physics, Electronics, and Applied physics. When I left high school I had a 5 on the AP test and thought I was the shit… I was wrong!
I skipped my first physics class in college (151) and tested out of 152. Putting me in mechanics. Needless to say i failed. Now I am a triple major. I work hard and would assume i am relatively intellegent, but i got a D mechanics one. Why? because my background in physics was terrible. So many of the basic concepts i didnt have, so many idiosynchrasies i didnt know, so many analytical skills i was missing. This is the biggest mistake of my college career, and serves as a stain on my record. 4.0 with a D in a major class… which i have to retake. Now im in mech 2 and doing wonderfully, but this is because i learned from mech 1 what i should of learned last year.
A distraught failure…
Bryan
I can’t speak to the AP Physics exam, but I was very happy with the Calculus exam. My high school (a public magnet school in Baltimore) covered a whole lot of calculus, so doing well on the AP test saved me from wasting a whole lot of time. As it was, we were still covering stuff that I had seen in high school when I took multi-variable calc in college. On the other hand, I do wish that differential equations hadn’t been my first college math class. That was disorienting.
I had the same experience(2001), except that I admit I went to a rather anomalous public high school. We also offered regular, honors, AND AP classes for many subjects.
pre-meds may do alright on the Physics MCAT, but they dont’ actually learn conceptual physics. Which is pretty evident when they struggle through a lot of physiology material in 1st year that is for all intents and purposes applied physics (fluid dynamics).
I got the dates wrong above; it should have been 1984-85 and 85-86. Obviously my brain is not the well-oiled machine it was in high school.
My HS had no AP physics course, and effectively no physics at all. (I did better on my physics SAT than anyone who took the crappy physics course we had.) The chem teacher, on the other hand, was the shiznit. We had three years of chem: inorganic, organic, and AP. I placed out of 2 years of chem with a 5/5 on the test, leaving me the choice of Orgo or P-Chem as a freshman. It was at that point that the system failed utterly; I took P-chem, thinking naively that it would be about, y’know, physical chemistry. Turned out to be a badly-taught Quantum Mechanics course. The chem AP was utterly irrelevant to it (Calculus would have been necessary but not sufficient).
I got my gentleman’s C and was happy to get out alive, but it left me disillusioned about the level of understanding among professors as to what was actually on the AP tests.
I can speak only of ancient history – private boys’ school in 1967-68, where I took AP courses. I did not take the exam. I found that my high school course was very good preparation for the entry physics courses at Georgia Tech. I think it would have been a mistake to skip that course, despite the fact that it was taught in an auditorium with more students than in my entire department when I was in graduate school, and exams were graded strictly on the basis of the answer (no partial credit for using the right method – sign error leads to bad grade).
Maybe I’m not normal (OK, probably I’m not) but I found that real understanding came only later, after the courses. Except for the best students, I think people come out of AP and early college courses with the ability to take the tests, work problems, and answer questions, but with little real understanding. However, I have to say I think I didn’t have some of those misconceptions you talk about.
I’d like to enlist your advise and the advise of any readers who can provide it. I teach physical science to pre-service elemntary school teachers. I try to ellucidate the somewhat subtle differences between the application of a force and the just getting in the way of, among other things, and I try to point out why this isn’t just semantics but truly important conceptual skills. I’m not sure they hear me, or how well they hear me, they rarely do well on these questions on my tests. If you can try to go back to the very basics to teach an adult with a clean slate mind, how would you approach these topics, and which concepts in physics are most important for them to know? I might be able to squeeze two or three into their minds in the woefully short amount of time I have to do so. Thanks.
I took the Physics C exam without taking the corresponding AP class. I got a 4, tested out of the first semester of college physics, and nearly got a “C” in the second semester. When it came time to take the GRE, I was really shaky on simple mechanics, collisions, pulleys, whatever. It definitely lost me some points. I hadn’t seen them since high school, and then only in a textbook. I only learned all this stuff for real when I TA’d the first semester course that I had skipped.
But I expect my experience had more to do with the fact that I did it as any independent study than anything else. Taking the class, doing the homework, doing the labs, all more important than I thought at the time.
I didn’t go through the US system, but I find the conceptual basis for the AP tests appalling.
To truly learn things like physics most students need repeated exposure of thematically linked classes that build on the previous results and provide multiple modes of learning – that means labs and homework as well as lectures and reading.
To be really prepared for university level physics students ought to have 4-5 years of physics, supplemented by labs, starting with algebra and geometry based mechanics, and moving on to calculus based physics in the later years. Each year’s classes need to build on the previous material and provide refresher overviews at the beginning of the academic year.
There are always natural geniuses who will learn, or figure out the material, no matter what. And there will always be some who are lucky with a particularly apt teacher or combination of classes, but for the average very good student you need repetition and practise.
To take a crude analogy: there are natural athletes who can play american football competitively in college without having seen the sport before, but for most good players, the essence of their performance is familiarity and practise over many many years.
Stein, you’re not criticizing AP tests, you’re proposing an alternate reality.
If you take AP tests and do well, you’ll generally have one year of high school physics, and then start second semester physics as a freshman.
If you don’t take AP tests, you may or may not have one year of algebra-based physics in high school, and then start first semester physics as a freshman.
Me, I think AP stuff is great. It’s entirely reasonable and plausible that a year long high school course for smart students can do the same thing a semester long college course for typical students, and it gives bright students a reason to show up mentally for high school, after they’ve already been accepted to college.
I took the AP Physics C (or whatever the calc.-based mechanics-only Physics AP was called in the mid-90s) in highschool, received a 5 on the test and placed out of the intro physics class at my liberal arts college. The course was essentially taught as a half-year class with our teacher’s own epistemology curriculum filling out the balance of the time. I felt as well prepared for the second semester of college physics as my peers. Not that it helped my understand E&M any better. Mechanics and calculus made sense. Electricity made me an econ. geek.
hogeb —
Here’s what I would suggest. Other physics teachers should feel free to join in!
Clear up any confusion about mass and weight. Forget about units initially. You measure mass when you shake or heft something, like some people do in the produce section. You measure weight when you use the produce scale.
Mass measures inertia. When you shake something, you are testing to see how it reacts. If you can provide some suitable objects for them to try out, all the better.
Weight is a force, the force of gravity. There are many kinds of forces. The scale balances the force of gravity against the force of a spring inside the scale. The force of the floor pushing up on your feet balances the force of gravity on you. (You can talk about electrical repulsion between atoms, if you think they’ll buy it.)
Unbalanced forces make things accelerate (speed up, slow down, change direction — that last one is tricky, use your judgment). Without the floor pushing up on your feet, you’d accelerate toward the ground. To discourage the misconception of the floor “just being in the way,” see if any of them have been on the amusement park ride that drops your chair vertically (it’s the Hellevator here in Louisville). The seat is “in the way” but exerts no upward force on the rider’s butt during the fall.
More massive objects are harder to accelerate. Relate that back to the hefting/shaking idea.
Balanced forces result in no acceleration, which can mean (1) nothing is moving or (2) something is moving but not accelerating — it’s “coasting.” You can use ice skaters or air hockey pucks gliding as examples, or two kids balanced on a seesaw might work, too.
If you want to complete the discussion of Newton’s Laws with the third, you can borrow Paul Hewitt’s analogy of “you can’t touch without being touched.” The trick here is to make sure they don’t confuse balanced forces with action-reaction pairs. I have to stress to my kids that the 3rd law applies to two objects exchanging equal forces, not two equal forces acting on one object. To the novice, it’s easy to confuse the two.
I would hold off referring to units and invoking Newton’s Laws until you cover the above. If you can approach the Laws as just commonsense, as I do, you’ll probably encourage the wary that physics is not really that obscure.
Thanks Wheatdogg, especially that last part about the third law. I think that will really help them. I’m giving them their test on this tonight, so we’ll see how well I did this semester. I’ll print your comment out though, and stick it in my notes. Thanks again.
My pleasure. Let us know how it turns out.
Wheatdogg: Here’s a third law head scratcher that I always give my students. I wish I could remember where I got it from.
A book of mass m rests on a table. The table exerts an upward normal force on the book whose magnitude is mg. This is a consequence of (circle one):
(a) Newton’s 2nd law (b) Newton’s 3rd law.
Explaining why (a) is correct and, more importantly, why (b) is incorrect. It really helps clarify the distinction.
Another useful tool I have used, and have noticed appearing in more and more texts: use subscripts on vectors to denote “actor” and “acted upon”.
For example, F21 is the force that object #2 exerts on object #1. When computing net force, you are only allowed to add forces that have the same second subscript — they’re the only forces acting on that object!
In other words, Newton’s 2nd law becomes:
m1 a1 = F21 + F31 + …
Oops…in my previous comment I wrote “this is a consequence of”. Actually, I usually say “we know this to be true because….”
Also, there is an important caveat in the vector subscript rule above. It is tempting to write Newton’s 3rd law as: F12 = –F21.
I tell my students not to do this because it is an algebraic equation that can easily be transformed into: F12 + F21 = 0. This is nonsense, of course, because you are adding forces on two different objects. I usually say that Newton’s 3rd law says “F12 is –F21″, and that if you switch indices, you introduce a negative sign. I then go on to explain why they should try to avoid replacing “is” with “=” as above.
The fun part is when we get to systems of particles and conservation of momentum. Then I have to explain why it’s okay to break… okay change, my own rule. 🙂
Yes, I am proposing an alternate reality, one in which people who think about doing physical science at University arrive prepared, having taken a sensible curriculum in high school that permits them to receive actual grounding in the relevant academic subjects.
The rest of the world does it; the US does it for other subjects, including sports.
The issue with AP is not the test, or whether a one year survey class vs one year Mech and E&M class is worthy of college credit; the issue is that it is a ONE YEAR class, and most of the students are not going to walk away with any in-depth understanding of physics after one year.
To get instinctive comprehension of the subject, most of the good students need repeated multi=year exposure to overlapping topics that build on each other.
The current AP debate is deck chair rearranging.
Ja, Steinn! My point exactly. Somehow in the dim times of designing the high school curriculum in the US the experts made the decision on the bio, chem, phys order. Courses were compartmentalized. That was during the 1910s (or maybe earlier), when bio was not dominated by biochemical details, chemistry was a matter of stoichiometry (no atomic theory or QM) and physics was heavily mathematical. Then, it made sense. Now it doesn’t. Also somehow the experts decided that younger adolescents (aged 10-14) could not learn certain abstract notions of math and science, until their minds were “ready.” This change magically happened around age 14. (as if).
Nobel prize winner Leon Lederman has been campaigning for a wholesale redesign of the high school science curriculum, putting phys first and bio last. There are similar efforts to put more “beef” in the middle school science curriculum, similar to what the European schools do. It’s hard to say how long the process will take. Educators (and more importantly administrators) seem to be very stuck in their ways.
Ah, units. You hit on one of my favorite pet peeves. I think units are extremely important, because the numbers mean nothing without them, and the units themselves tell a story. Long after some of my graduate courses, a fellow student came to me for help when he went back for his PhD. We worked some problems that I remembered vaguely, but I couldn’t quite remember everything. Then I just looked at the units and said, “This is how we do it.” Cheating a little, I think, but units can certainly help clear up some issues.