Reading: “The benefits of completing homework for students with different aptitudes in an introductory electricity and magnetism course”


F. J. Kontur, K. de La Harpe, and N . B. Terry

I am trying currently trying to write my student materials for next year for my L2 Physics course. I want to base the mechanics unit on modeling instruction again, however I am trying to trim down from 2.5 terms of modeling to 2 terms (20 weeks). And although it seems like not much to trim down, every single lesson that I am getting rid of is painful.

I am trying to strike a balance between mastery of physics (with extended time spent of mechanics through a modeling instruction method), and some breadth to the course. I think with the extra 5-6 weeks we will do the optics unit. However I still want to have the conversation of “depth vs breadth” with the other teachers from around NZ and the powers who do control it all…

Back to homework. I am wondering do I write homework sets into my materials. As I wrote them I reflected on this year, and I realised only my top kids really completed any homework this year. Should I write it for next year? Should I enforce it?

A bit of reading led me to this article by F. J. Kontur, K. de La Harpe, and N . B. Terry (“The benefits of completing homework for students with different aptitudes in an introductory electricity and magnetism course”). They looked at not how a class may improve from homework, but instead how different aptitude students benefit from homework. They found “On average, successfully completing many homework problems correlated to better exam scores only for students with high physics aptitude. On the other hand, all other students showed zero or even a negative correlation between successful homework completion and exam performance. Low- and medium aptitude students who did more homework did no better and sometimes scored lower on exams than their low- and medium-aptitude peers who did less homework.” AHHH! What?! “Sometimes scored lower” …

it is worth noting that we as instructors assign homework to our students because we believe that all students will receive a learning benefit from doing homework. This belief is predicated on the idea that there is a strong positive correlation between making an honest effort to do well-chosen homework problems and student learning, qualities we attempt to measure using homework scores and exam scores. If there is no correlation between successful homework completion and exam scores, we should carefully rethink these assumptions, especially considering that assigning, completing, and grading homework is often a very time-intensive activity for both students and teachers.

Its worth noting that this article looked at the effect of both online homework, AND written homework. Online homework had negative correlations between completion rates and exam scores for medium and low aptitude students, and written homework had no correlation for these same students.

Not about homework, but I like this quote all the same: “As Redish et al. say, “We are frustrated by the tendency many students have to … spend a large amount of time memorizing long lists of uninterpreted facts or performing algorithmic solutions to large numbers of problems without giving any thought or trying to make sense of them

Kelly O’Shea writes a good physics teaching blog I follow and she has posted on similar thoughts here.

So it looks like, for this course at least, homework will stay out of the course. Certainly something that needs to be further investigated… One possible avenue is “interleaving”. This means that homework doesnt just focus on one topic, but mixes up  a number of different units. The research done on it (in maths) seems promising.


Reading: Depth Versus Breadth: How Content Coverage in High School Science Courses Relates to Later Success in College Science Coursework


Schwartz, Sadler, Sonnert, Tai

Depth or Breadth in high school science? The answer is a resounding “depth”. This is a study involving 7000 university students.

“…indicates that those students reporting high school science experiences associated with the group “depth present–breadth absent” have an advantage equal to two thirds of a year of instruction over their peers who had the opposite high school experience (“Depth Absent–Breadth Present”)”

“These appear to be that students whose teachers choose broad coverage of content, on the average, experience no benefit. In the extended model, we arrive at these results while accounting for important differences in students’ backgrounds and academic performance, which attests to the robustness of these findings. The findings run counter to philosophical positions that favor breadth or those that advocate a balance between depth and breadth”

“Students who experience breadth of coverage in high school biology perform in college biology as if they had experienced half a year less preparation than students without breadth of coverage, whereas those who are exposed to in-depth coverage perform as if they had had half a year more preparation than the students without depth of coverage. In chemistry, depth appears to be equivalent to one quarter of a year more of high school preparation. In physics, the effect is closer to two thirds of a year more preparation” 

Reading: Big Ideas in Science Education


Reminds me very much of the 7 cross cutting concepts of the NGSS in the US. These a little bit more specific, but I like the general idea of saying – “what is really important?”

  1. All matter of the universe is made of small particles
  2. Objects can affect other objects at a distance
  3. Changing the movement of an object requires a net force on it
  4. Total Energy is unchanged but can change from one form to another
  5. The composition and process of the earth affect its surface and climate
  6. Our solar system is a small part of the universe
  7. Organisms are cell based, and have a finite lifetime
  8. Organisms will compete for food, energy and resources
  9. Genetic info is passed down from one generation to another
  10. The diversity of organisms is a result of evolution

There are also 4 ideas about science

  1. Science is about finding causes of/in natural phenomena
  2. Scientific explanations, theories and models are those that best fit the evidence available at a particular time
  3. The knowledge produced by science is used in engineering and technologies to create products to serve human ends
  4. Applications of science often have ethical, social, economic and political implications

This list kind of answers the question – what is important for our kids to learn in science after they leave school.

There are a number of good readings at the bottom of the site too.

Reading: Categorization and Representation Physics Problems by Experts and Novices



This article definitely goes on the “top 10” list of physics education research. It is an early article in the field (1981), but been cited an immense 3600 times, meaning it really has stood the test of time.

The authors investigate the difference in experts and novices at solving physics problems. The novices being students who have finished a first year uni course, and the experts being wither PhD students or professors.

The first task required test subjects to group a bunch of problems together in sets that had similarities. Experts group problems based on the major physics principle (conservation of energy, Newton’s Laws) needed to solve them. Novices on the other grouped problems based on their surface features. These included objects such as springs, ramps etc, and key words such as force or velocity.

Later tasks delved deeper to further investigate the thinking process in experts and novices. Novices used the surface features of a problem to search for an equation. Once with an equation, they hoped it would lead them to a solution, or an intermediate solution where they could use another equation to further advance them.

Experts were sometimes able to guess the major physics principle involved after reading  only 20% of the problem. They further confirmed, or readjusted their view as they read on, and had planned an overall “attack” on the problem, knowing how to get to solution without mentioning or reciting a single equation. After the plan was clear, they could then start looking for initial values and choosing appropriate equations.

One piece of research I would love to do is to replicate this in NZ. Do our best and brightest (scholarship winners) think like this? Can we train students to think like this? Does a modeling approach seek to improve students thinking to this level?

Certainly a great piece of research, and I’m sure I will come back to it a number of times.

Reading: Misconceptions or P-Prims: How May Alternative Perspectives of Cognitive Structure Influence Instructional Perceptions and Intentions?

David Hammer


Alot of Physics Education Research discusses the “misconceptions”, or “preconceptions” that students bring into the classroom. Hammer discusses the theory of DiSessa that this might not actually be the case. Instead students might be calling on underlying phenomenological primitives, or p-prims.

The difference in the two is that “misconceptions” are fully formed structures or models in the brain.

“For example, in one popular demonstration of misconceptions, students were asked to explain why it is hotter in the summer than in the winter (Sadler, Schneps, & Woll, 1989). Many responded that this is because the earth is closer to the sun. T  see this response as a misconception is to understand it as part of the students’ knowledge system: The question accessed that stored (and faulty) element of knowledge about why it is hotter in the summer. Another interpretation would be that the students constructed that idea at the moment. This construction would be based on other knowledge, such as the (appropriate) knowledge that moving closer to the sun would make the earth hotter, but it is not necessary to assume that the idea itself existed in some form in the students’ minds prior to the question.

DiSessa (1988, 1993) developed an alternative account of students’ intuitive physics knowledge, positing the existence of more fundamental, more abstract cognitive structures he called phenomenological primitives or p-prims. By this view, how students respond to a question depends on which p-prims are activated.

For example, the question of why it is hotter in the summer may activate for them a p-prim connecting proximity and intensity: Closer means stronger. This p-prim is an abstraction by which one may understand a range of phenomena: Candles are hotter and brighter the closer you get to them; music is louder the closer you are to the speaker; the smell of garlic is more intense the closer you bring it to your nose. It may be through the activation of closer means stronger that students generate the idea that the earth is closer to the sun in the summer. That most people would have this primitive in their knowledge system, and that it has a high probability of being cued in the seasons question, is an alternative explanation for why many students give such a response.”

There are a number of other p-prims apart from “closer is stronger”, and these include ” actuating agency, dying away, resistance, interference, and Ohm’s p-prim”.

The author then gives a transcript of a discussion of motion with his high school class, and explains it in terms of misconceptions and p-prims. He doesn’t give us his opinion on the more relevant theory, but lets the reader see how the different frameworks might lead to different actions by a teacher.

Reading: An introduction to Physics Education Research

Robert Beichner


The article is a summary of the history of physics education research in the US. From beginnings with Karplus and Arons, to McDermott, and towards the big names of Hake, Hestenes, Beichner, Zollman and Fuller.

Its a good read, and hard to summarise (it is a summary itself). But it has helped to clarify how some of the ideas, and people fit together in this field. Its definitely a good read at this point in my journey through physics education research. Not sure how it would go as an actual introduction.

It also gives me lots of directions to go in terms of my readings. “4. Research Trends”, “4.1 Conceptual Understanding”, “4.2 Epistemology”, “4.3 Problem Solving”, and “4.4 Attitudes” all have a number of references I would to pursue.

Reading: Investigation of student understanding of the concept of velocity in one dimension

David E. Trowbridge and Lillian C. McDermott

Article (accessed through sci-hub)

This is one of the earliest articles (1980) into physics education research, and is written by Lillian McDermott, a professor at the University of Washington. Here she interviews a number of undergraduate students to check their understanding of the concept of velocity. She uses interviews students and shows them a demonstration of two balls on tracks. One rolls at a constant speed (A), and one slows down on a ramp (B). The due to the inital speed of ball B, the balls pass each other twice (see below)

mcdermott vel 1

Their results show a surprising number of students (who are in university physics courses) confused a number of elements of the question

  1. They often confused velocity and position. That is, students thought when the balls were passing, they had the same velocity
  2. Acceleration was also confused with, as often the ball B, when behind ball A (but with a higher velocity, and about to pass ball A) was said to be “speeding up”, although it was constantly decelerating (up the ramp)
  3. Some students disagreed with the concept of instantaneous velocity, that is when probed to think about the velocity of ball at “an instant”, they assumed that this concept doesn’t exist (“objects cannot really have a speed for an instant; for speed to be calculated, there must be an interval of time. For an instant the objects have no speed, just a location.”)

Further interviews involved a ball slowing down (ball B) and one speeding up, but they never pass each other. And there are a number of other conceptual question that were added to exams including:

Tell whether the following statements are ALWAYS TRUE:

  1. On the freeway, if two cars reach the same speed, then they MUST be side by side
  2. If two objects both reach the same position at the same clock reading, then they must have the same speed at that one instant. 

This article is followed by one on students understanding of the concept of acceleration.