This demonstration patch might be of interest for you and your students. It is a prototype patch that triggers when rolling over a moving target... The trigger area doesn't have to move, but the patch recalculates the position of the rollover zone and trigger zone size - so a moving/changing target is possible. It also has bonus calculations to orient an image to the direction of the mouse movement. Following the mouse orientation was first demonstrated by @mark so mine is an adaptation...
both the mouse orientation image and the shape image are based on using Projector actors as containers for stage objects. That way you can use a percentage of Width and Height scale of the Projector actor to determine the size of your trigger zone in relation to the overall Stage size. It then requires value scaling to align the object size and position to the centre point scaling of the Projector and Stage using a series of Calculators and Limit-Scale Value actors. What you have done with the Inside Range actors is the same in my patch.