Teach the controversy

Why aren't public school classrooms teaching the controversy surrounding the following theories that are currently held by many reputable scientists?

Geocentrism:
http://www.geocentricity.com/
http://www.fixedearth.com/

Flat earth:
http://www.theflatearthsociety.org/forum/

Hollow earth:
http://www.ourhollowearth.com/

Apollo moon landing:
http://moonhoax.us/

Jewish holocaust:
http://www.ihr.org/
http://www.codoh.com/

I'm not saying these should be taught INSTEAD of the dominant theories of astronomy, geology, and history. I'm just saying that the close-minded and intellectually suppressive public school system should promote the free exchange of ideas and stop railroading any ideas just because they don't align with the scientific establishment.