I tell students that one way to develop their characters is by including their thoughts and dialogue. I draw a speech bubble and thought bubble on the board and then we discuss the differences. Students always catch on quickly because they read comics. As a class, we practice adding thoughts and dialogue to an example story.
When it’s time to revise on their own, students draw speech and thought bubbles directly onto their paper with a colored pencil, so they can see the changes they’ve made. Another way to do this activity is by having students draw their bubbles onto Post It 
notes and then sticking them directly onto their draft.
posted by Amy Lin, Writers in the Schools