Elementary Music Standard 3. Listening and Analyzing. Music moves in sets of threes, meter. FREE video.
This is a video that I put together for my classes that goes with the song and recorded activity, "Take Me Out to the Ballgame" (from the old MacMillan 2nd grade series). However, it does stand alone.
Students, 2nd-3rd grades thoroughly enjoy watching it several times. It's not professionally done (my husband and daughter are the puppeteers) but it does the job of teaching that music moves in sets of threes. And it's cute!!