Standard 5. Reading and Notating Music.
This is a fun video that I put together for my classes that goes with the song from the older second grade MacMillan curriculum. However, it does stand alone without the song. You can use other familiar songs that have quarter and eighth notes.
Students, 1st-3rd grades will thoroughly enjoy watching it several times. It's not professionally done but it does the job of teaching one and two sounds on the beat.
I usually introduced that concept to first graders and then the names of the kinds of notes to the second graders.