What are some of the key points and factors to keep in mind about the troubles. And how would you explain the countries history to a child?
This is far too big a question to answer easily. I would recommend, as an introduction "Ireland in Conflict 1922-1998" by T.G.Fraser, at 89 pages it gives a very good and concise guide to the Troubles, and their origins, as well as a list of texts for further reading.