In this Ear Training video I discuss the concept of the Diatonic System in music: playing different chords all within the same key. To keep things simple I use the key of C Major. This video could be a good introduction to basic harmony on the piano. There is also a short quiz section where Geoff invites the viewer to identify the type of chord (Major, Minor, or Dominant 7th).
In this video, Geoff Peters plays various chords on the piano and invites the viewer to determine whether the chords are major, minor, or dominant seventh chords, as well as identify the key.