Why don't the American school teach the true history?

While I was learning about Canadian history I found out that Canada had a war against america. Americans attacked Canada and they come to Toronto but then Canadians raised and drove Americans back. Canadians attack back and they went to all the way to Washington DC. Canadians then set the fire on White House. Back then white house was not white. The reason why white house is white house is they painted the house white to hide burn woods. Isn't that funny? Also my Canadian friend told me that amaricans killed billions of Indians. Why American school don't teach about this?

Why don't the American school teach the true history?
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