# Background

I chose to take a gap year before starting graduate school and spent that year teaching computer science and math at Loomis Chaffee: a small boarding school in Windsor, Connecticut. It was a great decision. I got some teaching experience, learned from excellent mentors (in particular Hudson Harper), observed the cultural phenomenon of East Coast boarding schools, and lived through a real winter!

One of my favorite parts of the job was building and teaching an introductory computer science class. In this article I want to share some data about student opinions on the curriculum of that class, and reflect on the conclusions that lie within.

# The Curriculum

My formal introduction to computer science was through a survey of computational ideas and programming paradigms. This approach is very successful at Harvey Mudd, and it had a strong influence on my course. I went into the year with a few guiding ideas:

• to explore different computational ideas and paradigms
• to do a lot of projects
• to focus on creative problem solving (although toned down from Mudd’s standards)
• to spend some time doing web programming

This lead to the following curriculum, split over three terms:

• Fall: Programming Bootcamp
1. Python (emphasis on functional programming)
• Winter: Inside the Computer
1. digital circuits
2. assembly
3. Arduino
• Spring: Types and Web Applications
1. the Elm programming language
2. reactive front-end web applications

Each unit featured some kind of test, and each term included an individual, student-proposed project.

# Student Opinions

The general opinion was that the class was interesting but challenging. Throughout the year I heard the following (paraphrased, in some cases):

• “This class’s homework takes many times longer than my assignments for other classes”
• “I really think your expectations are too high”
• “Last unit was really interesting, but so is this one”
• “I was really proud of my work for [project X, Y and Z]”

These comments, and other information about the course as whole, are very interesting to me, but less useful for other instructors1. However, I also asked the students about their relative opinions on the different units within the course, which might be more broadly applicable.

## Data Collection

At the end of the course I asked the students to rank each of the five units we covered (python, digital circuits, assembly, arduino, and Elm)2 in terms of how interesting they were, how challenging they were, and how well the students ended up understanding the material.

I converted the rankings into numbers by giving a unit a 1 in some category if it was ranked last in that category, and a 5 if it was ranked first. The results are shown graphically below.

## Interest

I found the results here quite surprising. My impression from teaching the course was the students really enjoyed working with Python (because the language allowed them to say what they were thinking) and Arduino (because they liked the physicality of it). On the other hand, they seemed very frustrated with Elm much of the time. However, it seems that regardless of these different levels of perceived enjoyment, the class found Elm extremely interesting. Possible explanations include the inherently visual nature of web applications, the complexity of the applications that the students built using Elm, or perhaps just that Elm was the last unit covered.

Assembly is the clear loser here, although a few students added notes saying that they thought is was certainly a valuable unit. Somewhat surprising was the low ranking of Python. It was certainly true that our Python programs were less sophisticated, and a few students added that they had some prior Python experience.

## Difficulty

These results were also bit surprising. Arduino ranks low – expected since that unit emphasized experimentation and precision over conceptual difficulty. But Elm falls in the middle, which I found surprising.

Finding assembly at the top of the list might strike some as unusual, but our assembly unit was fairly complete. It involved a proper treatment of function calls, including tail-optimized recursion in one of the class sections.3 Barely above assembly is the digital circuits unit. Finding both assembly and circuits at the bottom of the list is intriguing because those two units struck me as the units that were taught in a manner most typical to that of a typical high school class: class-time was spent on lectures, and there were tests with reasonable frequency. Perhaps this is further evidence that lecture-driven classes aren’t a good idea in high school.

## Understanding

If this chart looks familiar, then it should – it’s nearly a mirror image of the chart showing difficulty. I had originally asked about both difficulty and understanding because I wanted to see if there were any situations were students found a topic difficult, but because of the class and/or their own determination they were able to master it anyway.

The sole deviation from the mirror-image of the last chart is the Python/Arduino switch: Python was (barely) ranked as harder, while also (barely) ranked as more understood. The difference probably isn’t significant, but it can be explained all the same: Python was indeed a deeper unit, but we spent a lot of time on it.

# Conclusion

During the final days of the year I sat down with Hudson (my mentor teacher, who taught the fall term with me) and we discussed whether the curriculum should change next year, and if so how. We entertained a wide range of potential changes, but in the end there were only two changes we seriously considered:

• Should we use a different language to teach web programming?
• Should we slow down the class a bit by dropping a small topic?

Given the apparent success of Elm, along with the solid pedagogical reasoning behind its use4, we decided to keep using it as our primary tool for web programming. Some other language might have a gentler learning curve, but we liked to the way that Elm forced us to teach not just web technology, but also clean application structure. In fact, we wanted to devote even more time to that by doing the quick HTML/CSS intro in the winter instead of the spring. We decided that circuits would be the best section to drop.

Of course, all plans are tentative. I moved back to California in June, and next year there will be a new computer science teacher with their own plans and ideas.5 In the fall the winds of change will blow through Windsor, Connecticut once again.

1. All in all it seemed to be a time-intensive but potentially rewarding course. If I were to teach it again I’d preserve most of the core structure, while focussing my attention on smoothing out some of the rougher homework assignments and enhancing the scaffolding for the homework to help students who are struggling get back in the game.

2. I taught a sixth unit: finite automata and computability, but this unit is omitted from the data because most of my class graduated halfway through it.

3. To my incredible surprise, when asked to write a recursive function in assembly on the test (Euclid’s algorithm for the greatest common divisor), one student wrote a tail-optimized version, even though that was not even suggested.

4. The reasoning behind using Elm was manifold. First it enforces a clean clean application structure which emphasises application state, transformations of state in response to events, and the graphics as a function of state; this way of thinking about applications is extremely useful and is growing in popularity (reactjs, etc). Elm also follows in the tradition of the highly-functional, powerfully-typed languages, which all programmers should eventually be exposed to.

5. Serendipitously enough the new hire is a young man who recently graduated from Stanford – the school I’ll be starting my doctoral studies at next year. The coincidence sparked a few draft-swap jokes in the math department at Loomis.