"We live in a different time"... As a parent myself, I see the same thing. It's very important for them to know the history and appreciate what it took to make things better now than they were before. It has been a historic struggle from many kinds of heroes and heroines. But like yours, my kids are in a very diverse environment also. And we have to realize that, as President Obama said a few years ago of his daughters and their friends, 'They're better than we were' (that's an imperfect paraphrase from my imperfect memory).

They need to know about all of it, as they reach the ages where it makes sense to introduce them to it, but when race doesn't even enter into their minds and their friends are all colors and nationalities and backgrounds, isn't that what Martin Luther King wanted when he had a dream? Plenty of racism and sexism and other discrimination remains, and there are places that haven't had the opportunity to learn tolerance firsthand, but in diverse places where people have learned to appreciate one another, these kids have the best approach.