Here are some useful links you can use to get acquainted with developing mobile apps on WP7:

Download the developer tools here:

http://developer.windowsphone.com/windows-phone-7/

Students can submit apps to the Marketplace for free after they have registered with Microsoft Dreamspark:

https://www.dreamspark.com/

A brief High-Level overview of the platform:

http://msdn.microsoft.com/en-us/library/ff402531%28v=VS.92%29.aspx

Some helpful code samples:

http://msdn.microsoft.com/en-us/library/ff431744%28v=VS.92%29.aspx

A very in-depth series of videos that you will probably want to watch:

http://windowsteamblog.com/windows_phone/b/wpdev/archive/2010/08/17/windows-phone-7-jump-start-training.aspx

Happy coding!