Lip Syncing--a fun way to practice for memorization

Yesterday we worked on memorizing I Stand All Amazed. Here's what I told them:
Materials: Nothing. That's so easy :)

"Do you know what lip syncing is?"
An older boy explained that it's when you pretend to sing, but actually no voice is coming out.
"Today we're going to take some turns lip syncing. I want you to mouth the words 'I Stand All Amazed' really clearly, but not to make any sound."
I mouthed the words by myself and then told them to try it with me, using my hand to conduct just like we were singing.
Then I had a kid choose a picture from the "flip chart" to take down--telling them they'd need to remember the words without the prompt. I told all the boys to lip sync while the girls sang and I told them that I wanted them to mouth the words so well that I would think they were really singing.
After the boys did it, I had them sing while the girls were able to lip sync. The girls made pretty cute lip sync-ers too.

Pros: This was so funny, especially for the older boys. A few of them were so good at it. In fact, they looked more into the music than they usually do even when they're singing.
I also like that even though they kids aren't singing half the time, they are thinking about the words and notes, so they are still practicing. You'd be amazed at what you can learn just by putting mental effort into something.
Also, the kids thought it was funny, but they still kept the song reverent. They were actually pretty still because they were focusing on lip syncing.

Cons: I didn't have any overt problems.
This activity was less fun for the Sunbeams, though I let them pick some of the pictures to take down. But that's the only thing I can think of that didn't go as well, and honestly, singing time for the Sunbeams this early in the year is so often them listening while the other kids sing.