When a student asks for help, many tutoring systems present a hint, along with some buttons. If the student clicks on a button labelled "Explain more," then the system gives the next hint in the sequence, which is usually more specific. If the student keeps clicking on the "explain more" button, then the system walks down the hint sequence until the final hint in the sequence is presented (called the bottom out hint). On the other hand, when the student clicks on another button, typically labelled "OK", then the system stops hinting and has the student go back to problem solving.
Many tutoring system take advantage of student's familiarity with the navigation buttons used on web browser and other software. They give students 3 buttons per hint: forward (= "explain more"), backward (which goes back to the previous hint, if any) and OK.