We have been born as Nephi of old to goodly parents who love the Lord.
We sang this line, then I called on someone to name their goodly parents "Joe and Sue Black" etc, then we sang it again, called on someone else to name their parents, and so on. We repeated it lots with no boredom because they all wanted a turn to say their parents names.
Then we sang the next phrase: We have been taught and we understand that we must do as the Lord commands.
This time I interspersed singing the line with calling on kids to say one thing their parents have taught them or one thing the Lord commands. Again, lots of repetition without boredom. This strategy works best with just a few words of talking then jumping back into singing again.
Four simple actions for the chorus:
We are as the army of Helaman (stand bravely with hands on hips),
we have been taught in our youth (pointer finger to head, indicating learning),
and we will be the Lord's missionaries (use your fingers to make a "missionary tag" on your chest)
to bring the world His truth (have your hands go around the whole world).