There not musicals.... there movies

#1 had a discussion today at school about musicals. He plainly stated that the entire movie is not a song so it CANNOT be a musical. It is just a movie with more songs. He was very curious when he got home if in fact he was right. I explained to him that movies have different genres and that yes High School "Musical" 1 & 2, and Hairspray are in fact musicals! I think he was very upset about it. Currently he is doing "research" to see if I am right.... He is watching Hairspray.