Data Gymnasia

Data Gymnasia is a free website for learning data science, built using open-source Mathigon technology. Content is written in a simple Markdown format equipped with special syntax for a variety of interactive features, including executable code blocks, editors for writing exercises, and interactive Javascript components.

Getting started

1. Run npm (the package manager for Javascript) from the command line to see if you have it installed already. If not, download Node.js, which includes npm.
2. Clone this repo by running git clone [email protected]:data-gymnasia/courses.git from the command line.
3. Run cd data-gymnasia to navigate into the directory, and then run npm install to install the Javascript dependencies.
4. Run npm start. Wait for the assets to be compiled, and then open localhost:5000 to view the website. The server will automatically watch for file changes and recompile.
5. Every course is a subfolder in the content directory. The URL of the Python course, for example, will be localhost:8081/course/programming-in-python.

Note that running npm start for the first time might take a significant amount of time, as it compiles the LaTeX code for every course. This will speed up significantly when using cached results the next time.

To make a new course, run cp -r content/_blank-course content/my-new-course-name (or just duplicate the _blank-course folder and change the name). You can get started by editing the my-new-course-name/content.md file. Note that you have to ctrl-c to kill the npm process and then restart it whenever you add a new course or a new section in a course.

Course Structure

Every course consists of a few different components:

• content.md contains the source code and metadata for a course. It is written in a custom extension of Markdown.
• functions.ts contains all course-specific TypeScript code.
• styles.scss contains all course-specific styles, using SCSS format.
• hints.yaml (optional) contains any messages that can be sent by Mathigon's virtual personal tutor.

The shared directory contains biographies, glossary and assets used by multiple courses.

Every course is divided into multiple steps, each with a unique ID. These IDs are used as function names in functions.ts when exporting the setup code for every section.

Markdown features

Structure

Your Markdown file should have one top-level header, which is the title of the course. Sections are second-level headers (two hashes). Breaks are indicated with a line containing only ---, and between any two breaks there should be something for the reader to do (e.g., a multiple-choice or fill in the blank question, or a [Continue](btn:next) button). After every ---, you should include a line that looks like > id: step-22 to identify that step. The step id can also be a descriptive string (> id: spectral-theorem).

Questions

1. Fill-in-the-blank questions or multiple-choice questions:

   The sum of 1.2 and 1.3 is [[2.5±0.01]], and a polygon with three sides is a [[triangle|square|circle]]. The most popular programming language named after a snake is [[Python]].
   

   The correct multiple choice answer is the first one, and they will appear to the reader in random order. Note that ± provides a tolerance for numerical-answer questions.

2. Put-these-in-order questions:

       x-sortable
         .item.md(data-index="2") REPL
         .item.md(data-index="1") Script
         .item.md(data-index="0") Jupyter
   

   The data-index values specify the correct order and must start from 0.

3. Select-all-that-apply:

       x-picker.list
         .item.pill.bblue.md $1 + 1 = 2$
         .item.pill.bblue.md(data-error="too-large") $1 + 1 = 3$
         .item.pill.bblue(data-error="too-small")  $1 + 1 = 1$
         .item.pill.bblue $1 + 2 = 3$
   

   Correct answers are indicated by the absence of data-error, and the data-error values can be "incorrect" or can include context-specific feedback by putting a line like mutable: Variables can be changed! into the course's hints.yaml file.

Equations and code

Inline code is supported with backtick delimiters and a language indicator in curly braces: `{py} 1 + 2`. The possible languages are py, jl, r, and code (the last of which gets no language-specific syntax highlighting). Code blocks are denoted with fences:

``` python
import numpy as np
np.random.standard_normal((10,10))
```

The currently supported languages are python, julia, r, markup (no syntax highlighting), markdown, bash, docker, git, json, makefile, sql, yaml, and toml. If you want to add more, visit follow this link, check additional boxes as desired, and download the resulting JS file to content/shared/static/prism.js.

Executable code blocks are supplied using Mathigon Markdown's support for pugs

    pre(python-executable)
      | x = 3
      | x

The supported languages are python, julia, r, and bash. The Jupyter kernels which supply these environments are listed in content/shared/shared.js.

Inline math expressions are supported using LaTeX syntax with dollar signs ($x^2 + 2\sin y$), and display math is supported with latex code fences.

``` latex
2x + 4y &= 10 \\
3x - 2y &= 14
```

One catch is that backslashes need to be escaped inside inline math expressions.

Boxes

Several box types are supported: theorem, definition, example, exercise.

::: .exercise
**Exercise**  
Find the volume scale factor of the matrix $A = \begin{bmatrix}
    1 & 0 & 0 \\
    0 & 0 & 1 \\
    0 & k & 0
\end{bmatrix}$ by describing how the matrix transforms a region in $\mathbb{R}^3$. 
:::

Note that you need two spaces after **Exercise** to ensure that it displays on its own line.

Text boxes

Students can write an answer (up to 500 characters, currently) into a box that saves their work:

    x-quill

Glossary entries

To gloss a term, use Markdown link syntax with a gloss:-prefixed link: [linear combination](gloss:linearcombination). Then add an entry in the content/shared/glossary.yaml file:

linearcombination:
  title: Linear Combination
  text: |
    A **linear combination** of a list of vectors $\mathbf{v}\_1,
      \ldots, \mathbf{v}\_k$ is an expression of the form

    ``` latex
    c_1\mathbf{v_1} + c_2\mathbf{v_2}  + \cdots + c_k\mathbf{v_k},
    ```

     where $c_1, \ldots, c_k$ are real numbers. The $c$'s are called the **weights** of the linear combination.

The glossary functionality is encouraged, because it helps learners use the material in an *a la carte` fashion.

Figures

Put your file in the images subdirectory and insert it into the text with

    figure
      img(src="images/gram.svg")
      p.caption.md The grid-line images under $A$ and $\sqrt{A' A}$ have the same shape; they are related by an orthogonal transformation. 

If your software produces PDF vector graphics, you'll want to convert them to SVGs with something like pdfsvg rather than using raster image formats.

License

This work is licensed under a Creative Commons Attribution 4.0 International License.