My kids love reading the Tuttle Twins books. My son is only 5 and I thought that some of the concepts in the books might be a bit over his head, but he surprised me when he asked me to read them all over again because he liked them so much!
The truth about free markets, capitalism vs. socialism, government over-reach, the federal reserve, inflation, etc is not being taught any more in public schools, because socialism is the new direction that our country is headed. If you are a parent who loves America and values freedom, like I do, it's our a duty to teach these concepts to our kids, so that they don't get swept up in the tempting (yet forever corrupt) "Free-stuff for everyone!" mentality of socialism that is threatening to ruin our country as we know it.
The Tuttle Twins series get's my full stamp of approval. Let the liberals rage all they want. America is great because of the concepts being taught in these books.