Grade Inflation at the University of Waterloo

A few days ago someone asked me for a copy of the article I wrote in 2009 on undergraduate grade distributions at the University of Waterloo over a 19 year period from 1988/89 to 2006/07. After re-reading the article, I decided it would be a good idea to place a copy of the presentation here in case anyone else may find it useful.

Looking back on the research in that paper, I still feel that although it is impossible to say exactly why there was a slow and steady increase in the proportion of A’s that were awarded to students over that period, that it was data worth presenting. It generated discussion on why we assign grades to the work our students submit, on what functions we want these grades to perform, on how we want to apply them. Most of all I consider myself extremely fortunate to have been given those data and the opportunity to share what I found at a local conference.

Grade Inflation at the University of Waterloo – Presentation (PDF)

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Happy Canada Day Y’All

Celebrations in my Atlanta apartment included the creation of a dozen butter tarts while listening to classic Canadian artists that I otherwise don’t listen to often enough: Leonard Cohen, Gordon Lightfoot, and Don Messer.



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Sewing r = cos(2θ/3) into my Backpack with Electroluminescent Wire

I recently finished sewing the polar curve r = cos(2θ/3) into my backpack with electroluminescent (EL) wire. It was neat seeing how math, sewing, and electronics could come together in an inexpensive project, so I thought I’d write a short blog post about its development.

The finished product.

The finished project: a glowing approximation to a mathematical curve.


Back in November I was sewing EL wire into an elderly MEC backpack. It was an idea inspired by the Adafruit Tron Bag, but the bag’s zipper disintegrated before I finished the project. Not wanting to give up, I decided to find a new backpack and start again with a more mathematical design.

Over the past few months I was a teaching assistant for a multivariable calculus course at Georgia Tech. My students and I were finding the areas bounded by polar curves using double integrals, one of which was a specific Rose Curve.

The Rose Curve

The equation r = cos(2θ/3) is a specific Rose Curve with four overlapping petals.

r = cos(2theta/3)

The curve r = cos(2θ/3) in Cartesian coordinates. And what the curve was supposed to look like after I finished sewing it onto my bag …

Knowing that this was the design I wanted to use, my challenge was figuring out how to shape EL wire into that pattern, especially as I am not tremendously experienced with hand sewing. Luckily, the fabric of my backpack has a repeating pattern of “dots” that resemble points on a Cartesian grid. If you look closely at the photograph above you can make them out.

I wanted to place the curve on the front of the backpack in an area that was about 21 dots wide. I decided to trace the curve onto that space with chalk, using the dots as a guide. I could then follow the chalk lines as I sewed the EL wire. But how would I make sure that my chalk lines were precise?

Mapping the Curve onto the Fabric

Getting out the old ruler, I estimated the horizontal distance between each dot in the fabric by measuring the horizontal length between multiple dots. I made 10 measurements, and then took the average.

Number of Dots Horizontal Length (mm)
3 9.5
4 12.5
5 15.75
6 19
7 22
8 25
9 29
10 32
16 50
20 62.5

On average, the white dots in the fabric are 3.15 mm apart in the horizontal direction. I then made a number of measurements in the vertical direction.

Number of Dots Vertical Length (mm)
6 13
7 15
8 17
10 21.5
13 28
14 30
20 43
24 52.5
29 62
36 77
Estimating locations of fabric dots with Desmos.

Estimating locations of fabric dots with Desmos.

On average, the dots are 2.15 mm apart in the vertical direction. Using these averages and scaling the curve to r = 10cos(2θ/3), I plotted the locations of fabric dots in the first quadrant in Cartesian coordinates using Desmos. The blue dots in the figure to the right are approximate locations of white dots on the fabric.

Essentially, if the curve is scaled so that each dot is exactly 1 unit apart in the horizontal direction, then each dot is 2.15/3.15 units apart in the vertical direction. And the petal curve I was using is symmetric about the horizontal and vertical axes, so I only need to find a few dots in one of the four quadrants to sketch the chalk lines, below.

chalk lines

Chalk lines drawn, ready for sewing!

The Finished Project

The finished project

The curve isn’t perfect. Oh well – nothing in life really is.

Some of the threads are already loose, and because I didn’t follow the chalk lines exactly I ended up with something that resembles the perfectly symmetrical graph above. Oh well. I learned a bit about electronics, how to hand sew end knots, and hopefully it’ll help drivers see me at night when I’m riding my bike around Atlanta.


Sewing with EL wire is actually fairly easy and safe. I used invisible thread for the sewing, and all of the electronics  I purchased online through Adafruit for about $30: they have an EL Wire Starter Pack that has everything I needed. And EL wire doesn’t get hot when it’s on (unlike LEDs), and I didn’t have to solder anything.

What’s Next?

Solar panels! Building a solar powered AA battery charger for my EL Wire design looks fairly straightforward. One design on claims to cost $4. We’ll see.

Posted in Electronics, Hobbies | Leave a comment

Cats Can Play Musical Instruments Too!

The Acro Cats show came to Atlanta for a few days, I went to see them perform on opening night. The grand finale consisted of a chicken playing the cymbals while five cats played various musical instruments surprisingly well, given that they were cats.

I’ve been basically watching cute cat videos for as long as youtube has been around, so on a deeper philosophical level, its kinda feels like finally seeing that band you really like perform live.

Bowling: Gregory the Groundhog vs Tuna the Cat. Tuna got a strike and won the match.

Bowling: Gregory the Groundhog vs Tuna the Cat. Tuna got a strike and won the match.

Balancing act cat.

Balancing act cat.

Yeah, a cat playing a guitar. Most impressive.

Yeah, a cat playing a guitar. Most impressive.

The lighting wasn't great, but the musical talent was, given that the band members we cats.

The lighting wasn’t great, but the musical talent was, given that the band members we cats.

Posted in Hobbies, Vacation

Good Morning

I woke up this morning to discover that the route of a marathon & half marathon included the street I live on. I feel like exercising now.

Posted in Vacation

A Lovely Batch of Cranberry Applesauce

6 gala, 4 honeycrisp, 1 bag of frozen cranberries, cinnamon, cloves, nutmeg and orange juice. No sugar. An hour of peeling, coring, stirring, mashing, and  taste testing. The result: a large, lovely, cranberry applesauce.

Next time, I’d spend less time removing apple skins. They’re apparently loaded with vitamins A, C, fiber, and antioxidants, and of course I would have had that much more cranberry applesauce in my freezer. It also would have been wiser to make this recipe when the fruit I was using was in season. But it turned out well nonetheless, and is wonderful on the morning oatmeal.

My cranberry applesauce

My cranberry applesauce

Posted in Cooking, Hobbies

Atlanta’s Unsheltered No More Public Debrief Outlines Survey Data and Next Steps

Interview data collected from 637 homeless people living in Atlanta was summarized in a public debrief that I attended yesterday. The data was collected with the help of 190 volunteers. I was one of them, and had the opportunity to interview 9 people on two different nights over the past two weeks.

The statistics were overwhelming. The interviewers recorded 642 hospitalizations in the past month, and 1,147 visits to the ER in the past 3 months. Doing the math, this would work out to costing the city $8 million over the course of a year. Granted, these calculations are based on self-reported figures, but they’re also based on only 647 individuals, and that in 2011 there were 2,400 homeless people living in Atlanta.

What happens now? The Unsheltered No More project is now working with 17 partner organizations to facilitate a process that will house the most vulnerable, chronically homeless people. Additional social services will be provided for them after they move in. Spaces for 700 have already been found.

Will placing 800 people in housing and providing them with additional support be cheaper than just leaving them on the street? A well known journalist and author, Malcom Gladwell, wrote an article in the New Yorker that sheds some light on this question. He describes a study in Philidelphia that found that “most common length of time that someone is homeless is one day. And the second most common length is two days. And they never come back.” But it was the small group of chronically homeless individuals that cost “the health-care and social-services systems far more than anyone had ever anticipated”. In other words, Atlanta’s Unsheltered No More project might save lives and save money at the same time.


Posted in Volunteering

North Carolina Ski Trip

Skiing in the North Carolina Smoky Mountains doesn’t compare to skiing in B.C.. But when you live in Atlanta, $125 for the equipment rental, lift ticket, transportation, hotel and two meals is hard to beat. Granted, that price was that low because I went with a group of 40 people, and the January weather was so warm that all the snow was man-made, but that’s ok. I had fun.

My trip was a small adventure that took me to the Catalahooche Ski area, about 3 hours north of Atlanta. I met a lot of interesting people, including two C-17 mechanics from the USAF. A C-17 is a massive military transport aircraft.  “The British and Canadians have them, too”, one of them said proudly. He’s right. If you’re following the news, you may have seen that Canada sent a C-17 over to Mali recently.

I met a lot of friendly people. A group of 5 and 6 graders invited me to ski with them. Most of them fell down less often than I did, but they’re smaller and closer to the ground, so I don’t think that’s a fair comparison.

Someone from the south asked me if I had made igloos when I was growing up in Canada. To be completely honest, I wasn’t sure how they were made until I got home and found a lovely 1949 NFB documentary, How to Build an Igloo.

How to Build an Igloo by Douglas Wilkinson, National Film Board of Canada

Now I want to fly back to Canada to make an igloo. Though part of this inspiration is from a recent article I read about a guy from Edmonton recently built a pretty rainbow igloo not long ago.

I took a few photos from my trip using my cell, below is one of them.

View from the top of Cataloochee

View from the top of Cataloochee

Posted in Hobbies, Vacation | 1 Comment

Volunteering to Build a Homeless Registry

With the help of social workers and police escorts I volunteered on Friday morning to interview homeless people for the City of Atlanta’s Unsheltered No More project, aimed at building its first homeless registry. It was a saddening, but positive and unforgettable experience that helped me understand the realities of living on the street.

My shift started at midnight, and began with coffee and a one hour training session where we learned how to stay safe, how to fill out their surveys, and why we were asked to volunteer. There are 2,400 homeless people in Atlanta that live on the streets and in and out of shelters. Plans are in the works for some housing to be built for 800 people, but the city needs a way to identify who the most vulnerable individuals are. Hence, the registry was needed, and volunteers were called to survey the homeless population. I was one of them.

By 2:00 am, I found myself on a team of 6 volunteers, two social workers, and two policemen from a special unit that specifically deals with homelessness. I was on one of the teams that drove and walked through downtown Atlanta, meeting men and women living on the street that were sleepy but  willing to share their experiences with us. Some of the questions we asked were difficult. Some of our questions didn’t get answered. We took our notes, handed out food and warm clothing, and carried on until 6:00 am.

In the end I came away with a better understanding of what it means to be homeless, and the data we collected will be used to help the city move individuals from the street and into stable housing. It was a unique event to be a part of, and like my other experiences, I was able to meet some other volunteers along the way.

Pictures from the event are in an article on a local media website, Creative Loafing Atlanta.

Posted in Volunteering

I’m Building an Arduino Robot

motorshieldAfter having taught a few undergraduate mathematics courses that apply calculus and differential equations to circuits, all the while not knowing what a resistor or a capacitor could even look like, teaching myself how to solder them into a circuit board was cathartic. Thanks to a previous episode of my favorite CBC podcast, Spark, I’ve been inspired to take up robotics as a hobby: below is a photo of my adafruit motor shield for the Arduino robot I’m assembling, slowly and carefully. A part of me wishes I had gotten into this hobby a lot sooner, but I guess the technologies I’m using have only been around for a few years.


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