I have a practice question involving drag and drop which scores a amximum of 6 points for one slide only. It's only scored to show the student's success and not scored for the whole course/module.

Problem is when practice is repeated the slide score ramps up. How can I clear the score from previous practice attempt?
thank you.

One way to do this might be to use a variable just to hold this page score, it sound like you may have done this already.
The page score can be zeroed by adding an on display action to reset the variable to zero. This should mean an subsequent approach or page refresh resets the vatiable and the user starts from a score of zero.