The concept of conflict resolution can be explored with children at the end of the WW2 topic. Support children to think about all the people that WW2 affected. (If possible, visitors with first-hand experiences  could be invited into school to talk to the children about this.) How did it also affect places and environments? Is it still having an impact? Discuss the fact that it was a 'world' war; how did it affect other countries? Do some research and allow the children time to discuss their ideas in relation to these questions.