Every good movie musical needs a sense of joy and High School Musical 3: Senior Year has that in abundance. There is exuberance to the movie that is both authentic and infectious. All of this is embodied by Zac Efron as Troy Bolton, basketball captain, drama club star and all-around good guy of East High. It’s a sickeningly sweet part, yet Efron, like Dramamine, keeps nausea at bay. As a singer, he’s pleasant though hardly memorable; as a dancer, he’s more Justin Timberlake than Gene Kelly. The key is the genuine emotion he puts behind both enterprises. Efron sells the picture with all his heart. That’s really why the girls squeal over him. In its wishful-thinking way, the picture taps into an aspect of growing up that gritty independent movies – with their wayward Larry Clark kids — tend to forget: the effervescence of youth. Perhaps that’s why children, who still have the capacity to be freely, purely happy, have latched onto the High School Musical movies with such devotion.