Timed Interaction in Storyline

Make sure that the objects of interest are interesting to engage with.  Create a response to the objects being clicked.  Give your audience feedback.  Then the easy part. 

Create a variable [ClickCount] that tracks clicks.

On each slide create triggers that will adjust variable [ClickCount] adding 1 to it each time the user clicks if the state of that object is [x].

For each object of interest give it two states that look exactly the same. [X,Y] 
Create a trigger for each object of interest that will change the state from X to Y. When the user clicks.



This will let the user click on an object and only have it count once to the progress [ClickCount] variable.   


Note that free navigation may need to be turned off so that the student doesn't skip key content.