There are lots of ways, like going to museums or reading textbooks in school and asking their teachers, but for me, the best way is to speak to old people. Obviously, we can only go back a certain amount of time this way but, by talking to the people that were actually there, children can get a much deeper sense of what it was like. Watching films and TV series gives us a general idea of what a period in time was like but it's mostly made up and, therefore, not an accurate representation of history, so for more recent history, I prefer to ask the people that were there.