To put it simply, if we could teach students to "not believe the hype" and encourage the kind of open and honest debate that we've often thought was part of our national discourse, it would be easier to avoid something like that in the future.
One of the difficulties that will make it easier for men like Hitler to grab power is the fact that we are pushing towards a great deal of standardization in everything we do, particularly in schools. We want to train teachers the same way, we want to train kids the same way, we want to be able to predict the way that people will react, something that will make it much easier for someone to manipulate them.
When you look at the fact that there are very few strongly dissenting groups of people, particularly groups that aren't spouting some version of the main stream media's talking points, it is not hard to believe that it will not be really difficult for someone to take advantage of that fact and rise to power by pushing the right buttons.
Again, to prevent that, we need to change the way we look at education and find ways to encourage students to investigate things they are curious about instead of trying to craft a standard curriculum that dictates what everyone will or should learn and when they ought to learn it by. Trusting people and in this case young students to make decisions for themselves is not something that comes easily to us, but when you look at the alternative and consider that it might end up being someone making the decisions for them... Perhaps it becomes more of an appealing option.