When I was in third grade, we had to memorize the planets. (Still not clear on why that's something a third-grader needs to know, but whatever.) We were told to memorize them as follows:
"My Very Elegant Mother Just Sat Upon Nine Pizzas.
Not too long ago, NASA took away the Pizzas. And what third-grader can live without pizza?!?
See the average 9-year-old's reaction here.