<!DOCTYPE html><html><head><title></title><style type="text/css">p.MsoNormal,p.MsoNoSpacing{margin:0}</style></head><body><div style="font-family:Arial;">Hi<br></div><div style="font-family:Arial;"><br></div><div style="font-family:Arial;">I am setting up a graphical custom-response problem.<br></div><div style="font-family:Arial;">In most cases, there would a solution to the question being asked, and the student sould respond with a numerical answer.<br></div><div style="font-family:Arial;">However, in rare cases a solution does not exist.<br></div><div style="font-family:Arial;"><br></div><div style="font-family:Arial;">Avoiding these rare cases in advance or handling them programmatically would require a lot of effort.<br></div><div style="font-family:Arial;">In contrast, handling them manually would be easy (because this is a graphical problem).<br></div><div style="font-family:Arial;"><br></div><div style="font-family:Arial;">So I thought to instruct the students, in case they think there is no solution to the problem, to respond with the string 'NA'. In the customresponse code I would intercept this string and mark the problem for that particular student to be hand-graded.<br></div><div style="font-family:Arial;"><br></div><div style="font-family:Arial;">Is it possible to do?<br></div><div style="font-family:Arial;">If yes: how?<br></div><div style="font-family:Arial;"><br></div><div style="font-family:Arial;">Thank you in advance<br></div><div style="font-family:Arial;">Itay<br></div></body></html>