Hints can be provided to students, based on the last response given, as well as the history of responses given. Here is an example of a hint produced by a Formula Response problem.
+ ++What is the equation of the line which passess through ($x1,$y1) and +($x2,$y2)?
+ +The correct answer is $answer. A common error is to invert the equation for the slope. Enter +$wrongans to see a hint.
+ +