Roberta Tevlin, Manager OAPT Newsletter, teacher at Danforth CTI
roberta.tevlin@tdsb.on.ca

Are you tired of reading answers from your students that just blather on and on about anything that is vaguely related to the question? It took me many years to realize that I needed to explicitly teach my students how to write a good answer. Dave Doucette’s workshops on giving students the H.O.T.S. (Higher Order Thinking Skills) started me on this path. Learning to write clearly also helps students to think clearly. In an earlier article, I presented an activity called Writing with the Four C’s. This time I would like to present something I call “Scrambled Science”.

Writing with the Four C’s works well with short answer questions. This technique deals with more complicated questions where students need to think about how to order their scrambled facts to present a clear answer. This exercise was inspired by an activity in the Perimeter Institute’s Mystery of Dark Matter resource. (If you don’t have this, you can, and should, get it FREE).

Suppose you have just finished the Wave Nature of Light unit and you want your students to discuss whether light is a wave (Huygens’ view) or a particle (Newton’s view). You present students with the following true statements:

1. Light travels at 3.00 x 108 m/s - the fastest speed possible.
2. White light is made of infinitely many colours.
3. When light passes through a narrow slit it spreads out.
4. Crossed polarizers can block anything from half to all of the light.
5. Sunlight reaches us by passing through empty space.
6. Light reflects with equal angles of incidence and reflection.
7. Light passing through two slits can form many dark and bright spots.
8. Light bends when passing from air into water.
9. A soap bubble displays brilliant colours.
10. Light passing through a prism breaks into spectrum.
    

Their first task is to label each statement as supporting the wave model or the particle model. The statements are provided with letters so students can discuss the statements more efficiently. For example, “I think that A supports neither model.”

After discussions, the sheet should look something like this:

1. Light travels at 3.00 x 108 m/s — the fastest speed possible. neither
2. White light is made of infinitely many colours. neither
3. When light passes through a narrow slit it spreads out. diffraction — wave
4. Crossed polarizers can block anything from half to all of the light. polarization — wave
5. Sunlight reaches us by passing through empty space. particle
6. Light reflects with equal angles of incidence and reflection. could be either
7. Light passing through two slits can form many dark and bright spots. interference — wave
8. Light bends when passing from air into water. refraction — wave
9. A soap bubble displays brilliant colours. thin film interference — wave
10. Light passing through a prism breaks into a spectrum refraction (dispersion) — wave
    

Now that they have organized their thoughts (and reviewed all of the evidence from this unit) they need to consider how they should organize this information to answer the question. A well-ordered answer is essential in making it a clear answer. They are to answer the question in complete sentences in 50 words or less. Forcing them to reduce their word count helps to make the answer clear. Here is my attempt:

Light exhibits the following wave behaviours that particles can’t manage: diffraction, refraction, dispersion, polarization, and interference from thin films, double slits and single slits. However, light travels through empty space. Either this fact is wrong or light can’t be a wave either.

I have included the worksheet for this activity, another for a quantum discussion of the same question, and a third one about dark matter, which was my original inspiration. Also included are the answer keys for each worksheet.

• Wave vs. Particle: activity and answer sheet.
• Quantum Evidence: activity and answer sheet.
• Dark Matter: activity and answer sheet.

I have also developed four new Writing with the Four C activities for the grade 9 Sustainable Ecosystems unit.

• Carbon Cycle: activity.
• Backyard Capacity: activity.
• Pest Control: activity.
• Matter Cycles and Energy: activity.

If you like either of these techniques and develop some other samples, please let me know and we could build a resource to put on the OAPT website for other teachers to use.

Tags: Light, Modern Physics, Pedagogy, Quantum