Explaining to actual kids is fun, and a good rationalist exercise. I recently told this to my two years old daughter, when she asked me what I was writing about, when I was preparing a blog article on my computer. (She liked the explanation a lot. She insisted that I repeat it to her for the rest of the evening.)

Daddy has a lot of books, but these five he likes most: The first book says that people should eat tomatoes, and cucumber, and carrot, and cabbage, and peas, and beans. The second book says that people should exercise, like do squats, or hang from a bar. The third book says people should talk nice, not yell at each other, and say 'please' when they want something. The fourth book is about a lady who taught dogs and dolphins. And the fifth book says people should not do stupid stuff.

But yeah, for more complex topics, 5 years seem like a more appropriate age. I wonder how well people are actually calibrated about this; whether the actual 5 years olds would understand most of the ELI5 posts. Maybe someone could do an experiment with real kids -- tell them the stories, and then report how they repeated the lesson using their own words.

I am looking forward to the "Being reasonable: smart robots and dead walking people" book. :D