Adult science literary has tripled since I was a kid, despite the shrill claims that teachers are incompetent, people are stupid and science education is "dismal" that we seen thrown around in consumer media and the advocacy-based segment of science blogging.  In reality, people are pretty smart about science, but it can be humbling and people are less confident about things that are difficult.

Nothing shows that more than asking parents themselves what questions from their kids they find tough to explain.  Kids are curious and it may take two or three levels of explanation to get the point across - and that isn't easy for anyone to do.

The Big Bang UK Young Scientists&Engineers Fair, which bills itself as the as the UK's largest 'science for kids' event (March 15th to 17th in Birmingham), did just such a survey and compiled the hardest ones from the 2,000 adults who responded; no surprise math and science questions were at the top.

How airplanes fly and how a rainbow is formed were tough for parents to explain and it's no surprise.  Physicists still argue over the details of how airplanes fly and rainbows require remembering numbers.  The scientifically curious audience is quite astute conceptually but in America and England we don't have the memorization and rote learning fetish they have in Asia so on standardized tests Asian kids do better, which leads to the 'education stinks, spend more money' rationalization.  Do they end up being more creative scientists?  Not at all. Plagiarism is a cottage industry in Asia (and that culture long ago infected Russia too, where no copyright or patent or trademark is safe, thus their 'Science 2.0' television channel effort, which is really Science 1.0 from about 1986 piggybacking on our respected brand) and few creative studies are produced there.

20% said they either invented an answer to hard questions or claimed no one knew the truth and 16% of respondents simply passed the query to the other parent.

Are you stumped by why the Moon can sometimes be seen during the day or why the sky changes colors?   If so, Andy Bloxham writing in The Telegraph got Science 2.0 fave Dr. Brian Cox to make a handy primer.  Now you have no excuses.