# Bug?: Bad equation rendering in feedback of Blackboard created quizes

Question asked by Niels Smits on Oct 10, 2018

Hi,

I have a question about rendering equations in the comments/feedback section of questions migrated from Blackboard.

1    When opening quizz-questions originally created in Blackboard in Canvas gives perfect results, but things go wrong when it is saved within the system and the exercise is opened again, or employed in a test: in the feedback/comment to the answer the original equation is messed up. In the question body or answer options things don't change.

2    When looking at a simple example equation : $1.96\times\sqrt{\frac{P\left(1-P\right)}{N}}$, in the exercise itself the following code is used, which is perfectly rendered:

<math xmlns="http://www.w3.org/1998/Math/MathML">
<mrow><mn>1</mn><mo>.</mo><mn>96</mn><mo>×</mo><msqrt><mrow>
<mfrac><mrow><mi>P</mi><mo stretchy="false">(</mo><mn>1</mn><mo>-</mo><mi>P</mi><mo stretchy="false">)</mo></mrow>
<mrow><mi>N</mi></mrow>
</mfrac>
</mrow></msqrt></mrow>[/itex]

3    After uploading and saving the exercise in the system, and opening it again, in the feedback  a different code is present:

<p>
1.96×
P(1-P)
N
</p>

BTW: In the question body the code remains the same as under 2.

4    When I look at the exercise that I created by hand (using the equation editor) within Canvas, the following appears in the feedback environment:

<img class="equation_image" title="1.96\times\sqrt{\frac{P\left(1-P\right)}{N}}"  alt="LaTeX: 1.96\times\sqrt{\frac{P\left(1-P\right)}{N}}">

So it seems as if Canvas changes the structure of the content of the feedback section by converting rich material into images by which the original content created within Blackboard (using MathML) is partially destroyed.

My question is: is this a bug of the system? I would say it is because content of the item body and item categories don't change. Apparently comment/feedback sections are treated differently by the quizz algorithm.

I hope someone can comment on this or may have a suggestion of how to go about in solving the issue!

Niels Smits

I looked further into the different environments within questions. It turns out that "question_text" and "quiz_comment" are treated differently when the Blackboard quiz is imported. For example when both environments contain the same plot, it is saved in a proper location when present within question_text, but not within quiz_comment. In the latter case the plot gets a "broken_image" class (probably because the original Blackboard location is maintained). For example:

QUESTION TEXT:
<div id="question_180871_question_text" class="question_text user_content enhanced">
...
<img  alt="$CANVAS_OBJECT_REFERENCE$/attachments/xid-1001001_1" style="max-width: 603px;">
...
</div>

QUIZ COMMENT: