Why don't Mormans teach their kids about Joseph Smiths hat?

It's Mormon with an 'o', and Mormons don't teach more than half of the church's history. They teach the story about the brave pioneers who prepared to burn the city to the ground when soldiers invaded, but they don't teach the part called "Mountain Meadows Massacre". You can google that story. They don't teach that the scroll from which J.S. translated the Book Of Abraham still exists and the translation is total baloney. Here is that story:
viewzone.com/mormon.html