Practical example of using git in a school

Monday 21 April 2014

I recently joined Le Wagon, hosting a 9 week-long bootcamp for entrepreneurs in Paris. My role is to teach people who have had zero programming education how to build a web application using Ruby on Rails.

Boris Paillard, CEO of Le Wagon, wrote the first batch of ruby exercises during last year’s holidays for the very first camp. Since then, the teachers and I worked on improving and extending these exercises.

In this article, I explain how we leverage git to create a great Teacher/Student workflow. I will use Le Wagon as an example, but this approach applies to any computer class.

Teachers write exercise templates

When we first ran the camp, students kept telling us they wanted a way to know if their code was correct. Exercises consisted only of a, and solutions were given at the end of the day through live-coding sessions. It was a bit chaotic.

How could we automatically check if a student’s answer to an exercise was correct? Well, it’s quite straightforward, let’s use TDD! We agreed on an exercise template:

|-- Rakefile
|-- lib
|   `-- exercise_foo.rb
`-- spec
    |-- spec_helper.rb
    `-- exercise_foo_spec.rb

This way, students would just run rake in the exercise_foo folder and get an auto-grading of their attempt.

How Git and Github is used by teachers

We created the exercise templates repository and added push permissions to all teachers. Then it’s just a simple collaboration strategy with branches and pull-requests. Each new exercise is created/refactored inside a git branch, and a pull-request is opened when the job is done. Here is a figure showing the GitHub repository (origin in the context of teachers):

Teachers push and pull to GitHub
Teachers can push and pull to the exercise templates repo

Students work on the exercises and submit their attempt

Enter the students. Each student will fork the exercise templates repository to their own GitHub account. Then,

  1. Students can submit their attempts using git push origin master, where origin in this context is the student’s forked repository.
  2. Students can get an update of the exercises using git pull upstream master, where upstream is the original teachers’ repository.

So each students has 2 remotes configured on their local exercises repository. Thank you, git! Here is a figure to have a full picture over the workflow:

Students push their attempts
Students push their attempts and pull exercise updates

Icing on the cake, teachers get a dashboard

With all the automation in place, you can see there is a way to automatically compute a student’s attempt and create a nice dashboard of the class. That way, we can see who is thriving and more importantly, who is having trouble.

We needed a way to be alerted when a student pushes an attempt, so that we can run rake, parse the rake results and store that into a database. Fortunately, GitHub provides us with Webhooks, so each time a student pushes, a POST request is sent to the pedagogic platform we built. The pedagogic platform will then clone and pull the student’s repository, cd to the exercise repository and run rake. It is summarized in the following sequence diagram:

Pedagogic Platform is notified by GitHub via a Webhook
What happens when a student git pushes

So putting all together, we get this great Git workflow:

Git is powerful
Students push, GitHub notifies, Pedagogic Platform grades

Conclusion: Git is awesome!

Using git remotes, we managed to create an efficient workflow where teachers can easily update and add new exercises, while students are working. The Webhook provided by GitHub are priceless, thanks guys!

Follow Le Wagon, we have great stuff coming. If you are in Paris in July/August, or October/November, there are still some seats left for our 9 week-long bootcamp, they won’t last long!

Would you like to learn programming? I am CTO of Le Wagon, a 9-week full-stack web development bootcamp for entrepreneurs, and would be happy to have you on board!

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