We are unable to tech support and troubleshoot the many options for "casting" to a TV for your personal use. However, here are a few items that may help you to achieve seeing your classes on a larger screen. Using a Chromecast Device with your TV.  Chromecast by Google allows you to cast from Apple Devices, Android Devices or a Desktop using the Chrome web browser to a TV that has Chromecast Device.  Here is a Tutorial on how to cast from different devices.