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16 March 2011

Why (or why not) teach physics first?

I hear several common arguments advanced about why physics-first is a good or bad idea. Thing is, having been in a successful physics-first school for 11 years, the common arguments don’t stand up to scrutiny. The true reasons that I think physics-first can work are rarely mentioned in literature or conversation. Read on…

Four arguments that I have frequently heard about freshman physics:

#1) Since physics concepts underlie those of chemistry, students must learn physics in order to better understand chemistry. Only the merest kernel of truth. Yes, electrical attraction along with quantum rules define the structure of the atom, as well as the chemical interactions that an atom may have. Not even the most advanced freshman physics student will develop a deep enough knowledge of electrical attraction or quantum rules to assist in understanding chemistry. Okay, sure, a first-year physics course can deliberately do some introduction to atomic structure as a prelude to chemistry. So what? Most everyone was supposed to have learned the structure of the atom in 7th or 8th grade. Who says we can better teach that under the auspices of physics rather than physical science or chemistry?

#2) A deep understanding of physics requires mathematics beyond the freshman level. Not true. It is easily possible to teach conceptual physics with no explicit algebra required. Such a course can still teach the “Big Three” skills. Yeah, I’ll grant you that alumni of a freshman conceptual physics course are not ready to do the advanced waves/optics/quantum sophomore undergraduate sequence, but that’s not the point of high school physics.

#3) Physics involves more equipment that students can see, feel, and touch… more concepts within the realm of students’ prior experiences. And, so, physics is a better stepping stone into more abstract sciences. True, assuming physics is being taught correctly. A freshman physics course that consists of a teacher solving math problems on the board is doomed to failure. However, a successful freshman physics class allows students to test their predictions with actual carts, springs, balls, boats, lenses, resistors, lasers… and that is a perfect introduction to rigorous science.

#4) Physics is simply too difficult for general population freshmen. A descriptive biology course is more likely to promote success in students who don’t have a future in the quantitative sciences. Possibly true, possibly defeatist. If a school does not have teachers who are willing and able to teach freshmen physics enthusiastically and appropriately, then students are better served by a descriptive biology course, taking a physics course in college or as a more intellectually mature senior. However, with appropriate teaching, even general freshmen can be successful in physics; and some of these folks might see that they’re NOT actually shut off from a future in the quantitative sciences. I know my school has seen a non-negligible number of initially pessimistic students discover an interest in physics through our freshman course.

Two arguments that I rarely hear, but that are the most important reasons that we teach 9th grade physics:

Many freshmen will at first struggle with or rebel against the “rigorous” problem solving required in physics. By the end of the year, though, the class is comfortable with the problem solving process. They thus have little trouble with the more abstract problems in sophomore chemistry. YES! Something like 20% of our sophomores are new, having not taken freshman physics. Except for the very top-end students, the new sophomores exhibit the same initial struggles with chemistry that our freshmen did with physics. Our conclusion: the first rigorous, quantitative high school science course, whatever the content, presents intellectual obstacles to the general population of students. Those obstacles can be overcome just as effectively by freshmen as sophomores. The question is, do we want to teach chemistry or physics to these freshmen; then we’re back to argument #3 above.

It is politically easier to sell a required physics course to bright, enthusiastic new freshmen than to grade- and college- focused upperclassmen. The most important truth of all. Because so many of their parents fear physics, so do our students often fear physics. Our freshmen, and their parents, just accept that physics is the required science course that everyone takes. There’s little drama – students try to do what the teacher asks, they see their grades improve if they work hard; it’s just another class. However, an upperclass physics course takes on heightened significance in students’ minds. A poor start to the year in 12th grade physics causes anger and resentment – “This course is keeping me from getting into a good college!” Even before the course starts, the gossip amongst the fear mongerers will prejudice students. The initial attitude of freshmen toward physics is generally open-minded neutrality – they’re so busy adapting to everything high school entails that they don’t think about physics beyond the next day’s homework. But to teach a class of general-level seniors who arrive with their jaws set, their eyes narrowed, prepared to game their grade with every trick they know – that’s a setup for disaster.

Please understand that I don’t believe that physics-first is the correct approach in all situations. A successful physics-first program requires top-rate, dedicated 9th grade physics teachers, as well as a supportive department and higher administration. If any of those pieces is not in place, 9th grade physics might not work, and the bio-chem-physics sequence might well be more appropriate. In today’s and yesterday’s post I merely deconstruct arguments so that the potential of a 9th grade program (or the necessity to maintain a physics last sequence) is not dismissed out of hand.



  1. I hate teaching freshmen physics. The freshmen are immature and unruly. Also, 9th grade physics is basically just another algebra course so that the students get a double dose of math. Why not keep the sequence where 11th and 12th graders take physics and give them the option to take AP Physics as seniors if they are in 11th grade? Freshman physics is just dumbed down physics. I absolutely hate teaching this course (yes, I use Modeling Instruction) and I am looking for a school that doesn't offer physics first.

  2. I’m sorry you feel that way. I teach freshman. We teach rigorous physics - I do take offense at the phrase “dumbed down.” I will gladly have my freshmen challenge your juniors to some physics fights. :)

    But yes, freshman physics requires very strong class management because 14 year olds can indeed become unruly if we are not careful.