This is another idea I read from someone else's blog or website. I just can't remember where. Sorry. So anywho, I don't take any of the credit:) Since I do buy 90% of our groceries at Costco (family of 6!), I specifically went to regular grocery store in search of a dozen count egg carton without any windows that the marble could fall out of. Sheesh! It took a few weeks, but I found one.
I randomly wrote numbers from 1-12 in the bottom of the carton. I placed a large marble inside. On the inside of the lid, I wrote a numbered list of different ways to sing a song (like a skunk, girls only, under water, and so forth). I would choose someone to shake the marble around inside the closed carton. Upon opening it, the number that the marble landed in would instruct us on how to sing the song. I can easily change the numbered list of ways to sing at any time to better fit the type of songs we're working on. It can be used over & over again!