[LON-CAPA-users] Forcing students to submit valid expressions for formula responses.

[Angus Findlay]

When I give students formula response questions some of them don’t submit valid mathematic expressions. The most common problems are:

1) Not having balanced brackets. (i.e. number of left brackets do not match number of right brackets)
2) Including invalid characters, such as quotation signs.
3) Not including brackets, when necessary. (eg. 2^-1/2 instead of 2^(-1/2))

I want to tell them that the expression is invalid, tell them why, and allow them to enter it again, without penalty. (Right now my LON-CAPA server times out on them, and asks them to try again later.)

Is there a piece of standard code I can use for this, or if not, what it the easiest to implement a solution to this?

Thanks in advance.

Respectfully,
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Mr. Angus Findlay
Math Department, Mount Allison University
Sackville, New Brunswick

email: afindlay at mta.ca    tel: 506-364-2592
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