I am creating differential equation questions for uploading in Canvas via zip QTI. As you may think I write something like
\[ y'' + y = x+1 \]
in the body of the question. I tested the question in a HTML display and it was ok, BUT when I build a QTI file for Canvas and upload it, the formula was not correctly displayed.
A workaround is to replace y'' with \frac{d^2y}{dx^2} which displays correctly but simply y' would be preferred.
Interestingly, the issue only occurs when using Rnw exercises but not with Rmd exercises and when using the pandoc-mathml converter (while pandoc-mathjax would work correctly, for example). It can also be replicated using exams2html() when using the following options that correspond to the setup used in Canvas:
exams2html("diffeq.Rnw", converter = "pandoc-mathml", mathjax = TRUE)
Luckily there is a simple workaround, namely in Rnw exercises use y^{''} instead of the y'' that you would use in Rmd exercises. And then make sure you use converter = "pandoc-mathml". See below for simple worked examples for the exercise files.
R/LaTeX version: diffeq.Rnw.
\begin{question}
Is this differential equation showing up correctly?
\[ y^{''} + y = x+1 \]
\begin{answerlist}
\item Yes
\item No
\end{answerlist}
\end{question}
\exname{differential equation}
\extype{schoice}
\exsolution{10}
R/Markdown version: diffeq.Rmd.
Question
========
Is this differential equation showing up correctly?
\\[ y'' + y = x+1 \\]
Questionlist
------------
* Yes
* No
Meta-information
================
exname: differential equation
extype: schoice
exsolution: 10