Knock Three Times by Tony Orlano & Dawn is in D at 100 beats per minute and runs 2:31 across 27 bars. It uses 6 chords — D, G, Em7, A7, D7, A. The chord diagram changes as the song plays and the words light up as they are sung, so you can strum and sing along without reading ahead.
Want the melody line note by note? Knock Three Times guitar melody tab.