Remediation

There are several ways. Primarily you would look to add an action on the practice question and set the trigger to be when the learner fails an attempt. (There are several special triggers when on a practice question page.) 

The trigger will be when user gets the fail attempt (or final fail), and then you should show a message and/or button.

The button could open a page in the lightbox (e.g., a previous page) or could be a branching page to another page or you could display the remediation information. 

NOTE: The advantage to a lightbox option is that it eliminates the need to create navigation back to another page.

FYI in 7.4.3 there is a new option to show multiple pages in a lightbox.