What is the dance film where they are just a bunch of kids in detention?

What is the dance film where they are just a bunch of kids in detention and they get a new detention teacher and he teaches them to dance, and in the end, two of them preform and when they do they pretend that there the only ones there. (the others preform too but this is the only bit i really remember.)

What is the name of this film?

What is a VPN?

VPN is (Virtual Private Network) were first used by companies to enable their employees to securely access internal systems such as email remotely (e.g. from home or while on business trips). Today they are increasingly being used for personal use by individuals to protect their privacy while online in public places (e.g. when using the wi-fi connection in a cafe) or in a country where the internet is censored / blocked (e.g. China, Saudi Arabia…).