Is Pluto a planet? A 5th grade debate using the official rules

1. Ask: "Who has heard that Pluto is not a planet anymore?" Explain that in 2006 astronomers agreed on a definition.
2. Post the three rules: a planet orbits the Sun, is big enough that its own gravity makes it round, and has cleared its orbit of other objects.
3. Groups take the cards and test each object against the rules with sticky dots.
4. Share results. The Moon fails rule 1 (it orbits Earth), and Pluto and Ceres pass rules 1 and 2 but share their areas with many other objects, so they are dwarf planets.
5. Debate: half the class argues the rules are good, half argues for a change. Each side gets two minutes and must use a fact from the cards.
6. Close with what NASA lists today: eight planets and several recognized dwarf planets, including Pluto, Ceres and Eris.

Safety: keep the debate respectful with sentence starters and a timer.

Differentiation: students who need support test three objects only (Earth, Moon, Pluto). Students who are ready research one more dwarf planet and present it. English learners can use "___ is / is not a planet because ___."

Quick check: ask: "Which rule does Pluto not meet, and what does that rule mean?"

Educators, how do you answer the Pluto question when students bring it up? Share what works in the replies.