Human Skeleton Interactive - Placing Landmarks on an Image

I am in the process of creating an unfolding case study for our Nuclear Medicine technology learners. In this case study, the learner needs to place markers (X's or small circles) onto a skeleton image and receive feedback based on the accuracy of the marker placement.

The markers should not be labeled because it is not important that marker A be placed on the sternum or marker B placed on the rib cage left side.

Ideally, there would be several markers and the learner drags them to a spot on the skeleton image. I've attached an example but will probably look at reducing the number of markers and/or only having them mark the top half of a skeleton on one screen and the bottom half on another screen.

All ideas are greatly appreciated!

Michelle