To signal the end of class, this song works a treat.
The first half of the song has actions that can be followed. The second half is the song without words.
I sing the song through with actions the first time around and then when the instrumental part kicks in the students file out the door and line up.
As of writing, I also do “Head and shoulders” before getting into the goodbye song.
I start the two songs 4 minutes before the end of class and the timing works out just right.