Voila! There is a workaround!
Create music or voice-over in GarageBand. EMAIL it to yourself. It will be an .m4a format
From the email, press and hold the file and choose OPEN IN iMovie. Go to iMovie and name the file that downloaded.
Do the same thing with the movie file to which you need to add the voiceover.
Open the SONG file in iMovie. Use the icon at the top left to add the VIDEO file. They merge 'auto-magically'.
Go back to the Projects screen and you will have three files -- original song, original movie, combined project.
From the Projects screen, share the project to your cameral roll.
The send to iTunes will allow it to be played on a Mac if you have that option. We don't have Macs, but we do have Apple TV's with our projectors, so the students can present to their classmates or email a final project to a teacher or upload to iCloud or Dropbox.
Thanks for every suggestion. Step by step, I took bits and pieces to make this work for our students.
Life is good!