Why isn't Pluto a planet anymore?

Did it fall out of the sky?  Did it float away?  It is get in a fight with the other planets and decide it didn't want to be part of the group anymore?
No, no and (ha ha) NO!

Today's activity: Find out about WHY Pluto is no longer a planet.  Spend some time doing research and then in your Science notebook, on a new page write Pluto at the top and write down the answer to why Pluto is no longer a planet anymore.

These links might help, but feel free to go to other sites and find out for yourself.

http://www.space.com/43-pluto-the-ninth-planet-that-was-a-dwarf.html

http://www.wisegeek.org/why-isnt-pluto-a-planet-anymore.htm

http://www.planetsforkids.org/