The high school marching band performs a different routine every Friday night during halftime of the football game. These routines have many, many steps and constitute behavioral chains. When teaching each routine, the band director first shows the students the full show and then has the band perform the whole thing, while prompting them through it (e.g., "Keep going, remember, next, we will march forward for 8 counts."). Even though many of the students do not get all of the moves right during the first few tries, the band director continues to have them run the full routine over and over while providing instructions over the megaphone to guide them along the way. Eventually, the band director does not need to give any more instructions because the band is now carrying out the full routine without making errors or missing any steps. What teaching procedure does the band director use to teach the routine?