Day three began (after breakfast) with a session on Quantum Mechanics. The session was based around the 'Investigating the Nature of the Electron' activity from the Perimeter Institute's materials on 'The Challenge of Quantum Reality'.


The first task, 'Classical Particle Behaviour', uses very simple apparatus - sand and a paper coffee cup, to model the behaviour of particles passing through two narrow slits - Young's slits experiment. The task asks students to make a prediction of what they will see, encouraging them to explain their reasoning before continuing with the procedure of passing a small amount of sand through two narrow slits cut into the base of the cup.

As expected, two small piles of sand are obtained, reinforcing our understanding of the behaviour of particles.

Task two, 'Classical Wave Behaviour', again used simple apparatus (waves on transparencies, map pins and a cork mat) to model wave superposition, producing an interference pattern comprising areas of constructive and destructive interference.


The session developed these ideas further, incorporating observations made for electrons exhibiting both particle and wave-like properties. An animation was shown of the build-up of an interference pattern for single electrons passing through double slits. This experiment was first conducted in 1974 by Italian physicists Pier Giorgio Merli, Gian Franco Missiroli, and Giulio Pozzi, and was voted "the most beautiful experiment" by readers of Physics World in 2002.

To end this session we moved outside to the grassed area by the front door of the building, where a pair of speakers had been set up connected to a signal generator app on a smartphone.

sound interference

Session two dealt with issues of pedagogy - Johnsons' 5 Elements of Effective Group Work - which forms the basis of much of the very successful Cooperative Learning approach used throughout Canadian schools and beyond. An interesting discussion took place around the problems teachers have with group work tasks, and the strategies used to overcome these difficulties. Further discussion covered the nine ways that can be used to encourage positive interdependence in group work tasks.

johnsons elements

The third session of the day involved a piece of experimental work to Measure Planck's Constant, h, using some rudimentary electronic apparatus. This experiment is included in Higher physics course in Scotland and relies on a fairly large assumption to achieve its, frankly quite impressive, results. The assumption being that the energy transferred by an electron crossing the p-n junction of an LED, eV, is equal to the energy of the photon that is emitted from the LED , hf.

Planck Sheet

When conducting this experiment, my students use a PCB manufactured by jjm electronics for the purpose, where this version was a bit more 'kitchen sink' using a handful of individual components connected via croc-clipped wires to take measurements of the voltage at which each of the five LEDs would just begin to glow. This was easier to judge by placing the LED inside a black cardboard tube to view whilst adjusting the potentiometer.


Once the range of voltages had been obtained, they could be graphed against the known frequencies of light produced by each of the LEDs. This gives a beautifully straight line through the origin (even if you carelessly swap the axes, as I did), from which the gradient can be used to find Planck's constant, h.Planck graph

My wrongly drawn graph of f against V gave a line with a gradient of 2.8 x 1014, which in turn gave a value for Planck's constant of h = 5.71 x 10-34 J s.

This was the last session to take place at the Perimeter Institute for the rest of the day as we then left (on a big yellow school bus - quite a novelty for me) to visit the Institute for Quantum Computing (IQC) at the University of Waterloo. This visit continued the quantum theme of the day with a lecture on quantum cryptography, followed by a clever (if slightly too complicated for high school kids) practical task to model the transfer of information via quantum encryption. The group was then given a tour of the building, including a number of laboratories where the researchers took the time to explain their work and its applications.

After a final Q & A session we were whisked away to what was billed as 'Presentation preparation' in the schedule, but turned out to be the beginning of a group Challenge, with a visit to a dollar store. We were put into groups, given $10 and 20 minutes to told buy something that could be used to demonstrate an aspect of physics in one minute at a session later in the week. We were told that points would be allocated depending on the change that remained from the purchases, the ability of the group to keep to their 1 minute time slot and the quality of the demonstration. A few minutes of discussion settled on a few demos that could be done, followed by a frantic search around the store to find the required items before the deadline.

Returning to Perimeter for another delicious dinner, the group were invited to take part in a 'Crafts' session in the evening at the residence - this involved making our own washer and rubber bands model universes, drainpipe and rope 'mystery boxes' and obtaining hard copies of a number of the excellent Perimeter Institute resources avaialbe on their webstore.