Many students in the early Elementary grades get confused at the concept of counting hours on a clock. How many times do teachers have to come up with saying to get kids to remember hours/vs minutes? How about how many hours is it from 1:00 until 4:00? When students are first introduced to telling time and learning how many hours there are between times a helpful visual for them is to have a number line so they can view the numbers as linear and not circular. It is important to remember that the students should still have a clock in front of them as well. The number line is NOT a substitute for learning how to tell time on a clock.
This visual is probably best suited for lessons that do not use minutes or distinguish between AM and PM.