M20 subject report

Thursday 24 September 2020

In normal examination sessions, the Physics subject report is a treasure trove of advice for teachers and candidates: grade boundaries for each component, discussions about solutions to tricky multiple choice questions and revelations about the foundations of exam technique (write within the answer boxes!).

In May 2020, the examinations were cancelled. This means we're treated to a shorter report (just 4 pages) all about the Internal Assessment.

At a glance

A high quality investigation includes "well-defined research questions, clearly identified variables and a suitable means to measure and relate the variables, plus an appropriate and known scientific background".

These examples were considered interesting: analysis of a bouncing Tic Tac, the Q-factor of coupled oscillations, Compton scattering via simulation, reflection of light and polarization, and the use of a satellite database to investigate Signac interference.

Popular examples included: viscosity and temperature, the singing wine glass, the catapult, the Gaussian gun, coefficient of restitution and ball pressure, solar panel angles, refractive index and temperature, refractive index and concentration, measuring the width of a human hair with a laser, and variations on projectile motion.

It is possible to achieve 2 marks for Personal Engagement regardless of whether the student "[modifies] a traditional investigation... [designs] their own... [or uses] a standard method and standard analysis but in a thoughtful, detailed and competent way".

Exploration marks are enhanced when the investigation explores the relationship between just two variables.

We are reminded (again!) that students should take care when referring to the type of relationship during Analysis. The word "proportional" is often misused, and students are wrongly tempted to force the line or curve they are expecting through their points.

It seems that the Evaluation is hardest to master, but there is a route to success. Students should comment on "quality and range of data", compare "their result with the accepted value", consider "the viability of their result" and appreciate the "strengths and weaknesses of the methodology" with "realistic and relevant improvements as well as possible extensions".

The 12 pages recommendation is not a hard limit for "focused and concise" reports. Margins, spacing, scaling and positioning are far more important in Communication. Another tricky word to watch out for is "prove".

Unfortunately the information about popular IAs always comes too late for those of us doing the investigation in DP1! (Emma)

No surprises here, pretty much exactly the same advice as I have been giving for years. Not sure I would advise anyone to try to analyse the bounce of a Tic Tac though. Neither interesting or popular means good. (Chris)

Check your teaching

Make sure your students don't confuse the criteria with sections of the report; Personal Engagement is assessed throughout and not in the opening paragraph. Replace any nostalgia with "what the specific investigation was about, how it was conducted and what results were found".

Investigations should explore the relationship between a single independent variable and a single dependent variable. If this relationship is already known, the student should embrace this.

Ensure your students become fluent in analytical skills throughout the IB course. Measurements should be accompanied with raw uncertainties, spreadsheets should be used (without a need for sample calculations) and error bars should be presented. Significant figures should not increase as calculations go on and correlation coefficients should not be included.

Help your students to structure evaluations in investigations prior to the IA. How would a physicist judge the quality of their work?

Provide exemplar titles and research questions as a model for students to follow. Avoid photographs when a schematic diagram would be clearer. A reference list, not a bibliography, should be provided.

It's getting harder to steer students away from IA samples online... but the IB seem to be checking more for originality. (Emma)

Interesting point about the bibliography, I've always felt that this didn't really fit in with a physics investigation. Also good to hear officially that sample calculations are not required. It irritates me when students do this because they read somewhere that it was necessary. (Chris)

Important

The unit ms-1 is considered to mean "per millisecond".

Instead, students must henceforth be instructed to type the unit "metres per second" as m s-1.

Excuse us if it takes a while to amend this across ThinkIB and StudyIB! Will textbooks follow suit? (Emma)

Ridiculous! If a student writes velocity = 5 ms-1 I think it's quite clear what they mean. (Chris)

Source: Physics subject report, May 2020

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