I'm not a professional children's educator, but I am a mathematician with a huge amount of enthusiasm for educating children in mathematics from pre-school.
My primary activity is Puzzle Club, a mathematical exploration (currently) for my eldest son and his friends, from age 4.
I have also visited his School, where I talked about ancestry to the class.
The topic is how we all share ancestry very recently, within the last 600 years within Europe, and 2000 years worldwide. This is backed up by genetics (Ralph and Coop, PLoS Biology 2013). To quote from the abstract: 'Individuals from opposite ends of Europe are still expected to share millions of common genealogical ancestors over the last 1,000 years.' You may find the Popular Science coverage enlightening. Here are the slides, and (because they are wordless) here is an anonymised transcript.
For balance, I should say that there are some clear counter-examples: Native Americans were cut off from Eurasia 10-15,000 years ago; Australians and Papuans probably were even longer. We don't know about links to Africa, but the Egyptians certainly had contact and so are potentially the earliest ancestors shared between Africa and Eurasia.