Best Bets on TV Tonight

“High School Musical 2” (8 p.m., Disney Channel): You can’t get much more of a television event than “High School Musical 2,” which premieres tonight. After all, the first “Musical” was one of the most watched programs in Disney Channel history. And it ranks as one of the most popular cable TV movies of recent years. It’s spun off hit records and videos. The “Musical” has even been turned into a traveling production and is done in local high schools. Stars such as Zac Efron and Ashley Tisdale are household names — if you have a pre-teen in the house. The sequel is thematically close to the original. This time, the gang gets summer jobs at a resort and enters a talent contest.

“10 Days That Unexpectedly Changed America” (11 p.m., History Channel): This special features, among other things, a 1956 Elvis appearance on “The Ed Sullivan Show.”