Use an audio editing program and append 20 minutes of silence to the end of every track you use in your lessons.
You will be able to use the iPod and put all the tracks you want into playlists. After the song is over, it will "stop" playing. You'll have the freedom to advance to the next track, start from the beginning of the song, or pause the music anytime during the silence.
You will be able to use the iPod and put all the tracks you want into playlists. After the song is over, it will "stop" playing. You'll have the freedom to advance to the next track, start from the beginning of the song, or pause the music anytime during the silence.