You can plug in your audio jack (see picture below) that you normally plug into your computer into your iPad instead and the sound will play through your classroom speakers. Additionally, here is the links to an adaptor plug (VGA Adapter) Newer iPads & Older iPads. These adapters will plug into your VGA cord (picture below) which normally plugs into your computer to transfer the video. You plug the VGA cord into this adaptor instead and it will transfer the video.
audio jack
VGA cable