# Authoring questions¶

## Examples¶

See some examples on this website |examples_website|.

Content in OpenTA consists of exercises with one or many questions. An exercise and its questions are created using a custom XML format. For example,

```
<exercise>
<exercisename>Momentum and energy</exercisename>
<global>
m = 3 kg; v = 5 meter / second;
</global>
<text>
A particle with mass $m$ is moving with velocity $v$.
</text>
<question key="1" type="default">
<text>What is the energy of the particle?</text>
<expression>m*v^2/2</expression>
</question>
<question key="2" type="default">
<text>What is the momentum of the particle?</text>
<expression>m*v</expression>
</question>
</exercise>
```

## Mathematics typesetting¶

OpenTA supports typesetting mathematical expressions in text through
KaTeX. This means that whenever you
want to show some mathematics, for example
\(\frac{1+x^2}{\sqrt{1-x}}\), you write the corresponding LaTeX syntax within dollar signs:
`$\frac{1+x^2}{\sqrt{1-x}}$`

.

See the LaTeX wiki for a syntax reference.

For some more hands-on examples see this stackexchange collection (this is aimed at MathJax which also uses the same syntax).