Teaching physics for depth versus breadth

Throughout my trip I have visited some fantastic schools and met some great teachers who are teaching Physics in deep, meaningful ways using methods such as Project Based Learning and Modeling Instruction. However, there is a compromise which comes with teaching deeply: it takes time for students to develop their own understanding rather than just memorising facts and you cannot cover as much content as a traditionally taught course. As we all know, the teaching time we all have is limited. No matter how much time we have, as teachers we rarely think it is enough and as a result we need to make compromises about exactly what material is important.

This is the classic debate of teaching for depth of understanding versus breadth of content. This argument taps into fundamental ideas about why are we teaching students Physics in the first place – to get an overview of the academic discipline, to become scientists, or to develop the ability to think scientifically about the world around them? I believe we should be teaching them how to develop their own scientific explainations the world around them in scientific terms. There is no way we can teach them about every situation or scenario they will encounter in life – instead, we need to equip them with the skills to process information, analyse data and develop conceptual models of what is happening.

Unfortunately, in many places teachers are obligated to teach specific material due to a need to adhere to a highly prescriptive externally-developed curriculum and, often, a traditional written summative assessment of this content knowledge. This is the current state of Physics education in NSW and most of Australia, as well as in many other parts of the world and this reduces the freedom of teachers to make independent decisions about what topics are either important or interesting for their students.

Despite my lofty goals for why we are teaching Physics, Physics courses tend to be structured around making sure they touch upon all the ‘important’ topics in Physics: mechanics (motion, forces, energy, momentum), electricity (circuits, current, voltage, static charge, electromagnetism), waves (wave model, reflection, refraction, light, sound), and possibly a bit of modern nuclear and quantum physics. The NSW syllabus even touches on cathode rays, semiconductors and superconductors (topics not covered by your average high school Physics syllabus). So are we shooting for depth, or breadth? Take a look at that list and tell me.

In order to focus on deep understanding, some of the Physics programs I have observed here in the US have elected for their students to not sit external examinations in order to teach the subject matter more deeply. This is only possibly because the teachers and schools have a significant amount of independence and freedom and they have obviously garnered the support of their school community and administration.

How are these Physics courses assessed?

In California, High Tech High students have to sit the external state examinations. However, the school actively choses to not cover all the material which will be assessed, instead focusing on developing student understanding in specific areas. Historically, the students have performed well enough on these exams despite not covering all the topics, showing their deeper understanding gives them some transferable skills for processing information and analysing data in other topic areas.

In Arizona, there are no state examinations for the sciences. As a result, Arizona School for the Arts can assess students using the Force Concept Inventory, an assessment tool developed by the creators of Modeling Instruction which is design to evaluate common misconceptions in mechanics. This means that the bulk of the year can be used teaching mechanics in order to address and correct these common misconceptions.

New York State has state examinations for the sciences, the Regency tests, although students are not neccessarily obligated to sit all of them. Public school students have to sit one Regency exam for Science during high school, but it doesn’t have to be for Physics. This is interpreted differently by different schools, so that the Physics course at the High School of Maths, Science and Engineering is a course preparing students for the Regency exam. As a result, the teacher has to move a lot faster than he would like in order to cover the material.

In contrast, John Jay High School (also a New York State public school) has chosen for students to sit their Science Regency Exam in Earth science in year 8 or 9. As a result, the Physics course does not need to lead up to this examination and can have more flexibility in the content. Their final summative assessment for Physics, rather than being a traditional written examination, is an independent student investigation.

New York private school Trinity changed its Physics course a few years ago from a course which prepared students for the national SAT2 exam in Physics to only being an internally assessed subject which specifically does not prepare students for the SAT2 exam. The consequence of this change is that the course now covers a lot less content at a richer level. For example, they study mechanics alone from September until February! That’s the fundamentals of motion (excluding projectile or circular motion), forces and energy (excluding momentum) in around six months of school. For the Physics teachers reading this, you’ll recognise that’s a long time to spend on these topics… imagine the depth!

The overwhelming theme I see is choice and independence at least on a school level. To some extent, these schools have choice if students will sit an external examination for Physics, and some have chosen that the students will not so that they can teach in a meaningful way. However, note that these are not average teachers – I have specifically visited schools who are teaching Physics in interesting ways, so perhaps it is no surprise that they are bucking conventional exams.

So what about NSW?

The NSW system is not only highly prescriptive and externally assessed, but it is externally assessed with an examination so high-stakes it is almost unfathomable to people here in the US. Sure, 50% of our students’ HSC mark for the subject is based on internal assessment, but 50% is based on ONE examination. The results of their HSC examinations decide – basically independent of any other factor – what university and course they can attend. This is vastly different the the American university acceptance process, in which a college application considers a range of factors including all courses, sports, and extra-curricular activties undertaken throughout high school in addition to academic performance.

Does that mean that these approaches are not relevant within a NSW setting of prescriptive curricula and high stakes assessment? Of course not. Although I would love to say that it means we need to think about what is important and remove things from the Physics syllabus to reduce the content, I will more realistically assume that is not about to happen in any significant way. I have seen the Draft Australian Curriculum for Physics and although it may be an improvement on the current syllabus in some ways, it does not seem to be shooting for less content. Indeed, at the moment the year 11 course alone covers ‘Models of Thermal, Nuclear and Electrical Physics’ followed by ‘Models of Motion, Waves, Sound and Light’. Just as ambitious as ever! As always, the syllabus writers are focused on making sure students know ‘everything’ about Physics by the end (even if they don’t understand it).

So what’s a more realistic way we can teach for depth in the current year 11 and 12 NSW Physics syllabus? These are some of the things I’m currently thinking about doing in the year 11 course, based on some of the Modeling techniques I’ve seen here:

  1. Put mechanics first. Many schools and textbooks do this anyway, despite the NSW curriculum being arranged otherwise.
  2. Spend more time of mechanics than it may technically deserve according to the syllabus. In the process of developing a strong conceptual understanding of mechanics, students will also develop better skills in analysing and processing data which may allow faster progression through electricity and waves. Typically students struggle more with the mechanics unit anyway. I am going to steal as much time from the later units as I can possibly afford, and it still won’t be enough.
  3. Don’t immediately start with vectors! It’s only a confusing mathematical convention at the start. Bring it up where appropriate.
  4. Possibly start with a qualitative understanding of energy transfers and transformations in different simply situations before moving on to motion. Energy is, after all, the driving force behind most of Physics. (This is an idea I’m stealing from my visit with Frank Noschese earlier today.)
  5. Spend a signifiant amount of time develop student understanding of constant velocity motion through student experimental and analysis, then move on to investigating uniform acceleration motion. Use lots of motion graphs to describe these and get student very familiar with moving between these. I intend to use student whiteboards for this – lots of graphing motion and developing different representations of this.

Overall, the things I list above are fairly superficial modifications to the mechanics part of the year 11 syllabus. However, I have to work within the bounds of the curriculum to which I teach! Baby steps to change, and if moving towards a deeper understanding of Physics I think I need to start with building an understanding of mechanics in year 11.

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