How would students memorize all of those planets?
They wouldn't, answer Runyon and his colleagues. Instead, they should focus on the organization system of the solar system.
"Understanding the natural organization of the Solar System is much more informative than rote memorization," says the paper. "Teaching the zones of the Solar System from the Sun outward and the types of planets and small bodies in each is perhaps the best approach."
There are many who feel that the revised planet definition adopted by the IAU is technically flawed, since it doesn't address extrasolar planets or wandering 'rogue' planets - and, again, there's the whole zone clearing requirement, which many experts say no planet in our solar system can satisfy.
When I spoke with Stern about this last year, he didn't mince words.
"Astronomers aren't experts in planetary science, and they basically passed a bunch of B.S. off on the public back in 2006 with a planet classification so flawed that it rules the Earth out as a planet, too," he said. "A week later, hundreds of planetary scientists, more people than at the IAU vote, signed a petition that rejects the new definition. If you go to planetary science meetings and hear technical talks on Pluto, you will hear experts calling it a planet every day."