Quote of the Day: 30-8-2018

“When asked to draw a force diagram for some simple situation, most students emerging from any level of introductory physics course are likely to draw objects which look like a porcupine shot by an Indian hunting party – the number and direction of pointed entities being essentially stochastic.” ~ Arnold Arons (from R. Knight – “Five Easy Lessons”)


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” 

The Finnish model

From a teacher colleague of mine today: He wishes were operated in a Finnish model. In this model they are very “initial loaded” with teacher expectations. That is, their are strict entrance requirements on teachers into teacher education. It is a rigorous initial education scheme (masters I think?) and then once qualified teachers are trusted to be professional. In NZ this is almost reversed. Teacher training is not limited entry, training is not as rigorous (6 weeks in some cases – Teach First NZ), but once qualified, teachers spend a lot of their time jumping through hopes with NZQA (moderation), and the education council (for their inquiry).

I would love to see someone do some sort of cost-to-benefit analysis of the teacher inquiry in NZ with a typical secondary teacher. By cost I mainly mean time, and benefit is of course to the teaching profession.

I know I sound very cynical with this post, but after a very long day with a few unsuccessful lessons, and a whole heap of administrative hoop-jumping, I feel Ive earned it…

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.