What causes day and night? A simple question - key stage 2 stuff - with a simple answer: the Earth spins once every 24 hours. But does it? How do you know?
How would you convince a doubting Thomas who argued that the Sun moving around the Earth once every 24 hours was a much better explanation? After all, we can see the Sun move - it rises in the East and sets in the West.
And, if the Earth was spinning, when we jumped up, we wouldn't land in the same spot.
What is more, if your pupils are of a mathematical bent, they could work out that the speed at the equator was a little over a 1,000mph, which would seem enough to send anybody flying into space pretty rapidly.
My point is not to ask you to doubt the scientific account. Rather, it is that what seems the simplest of ideas is not so self-evident when challenged by the question: "How do you know?" or "What is your evidence?"
Achieving this kind of knowledge in science was a major intellectual achievement, hard-fought and hard-won through many years of debate and argument. Treating it as a commonplace undervalues science's history and those achievements. Yet few people seem to know the evidence on which our knowledge about the rotation of the Earth rests.
Moreover, questioning other fundamental tenets of school science, such as the idea that matter is made of atoms, that we live at the bottom of a sea of air, or that plants take in carbon dioxide and give off oxygen (in the daylight), and you will find the difficulties are similar, or even worse.
Even KS3 work and the new materials from the KS3 strategy seem to take the idea that matter consists of particles as a given, and not something to be argued for, post-atom bomb.
Why should we worry? In case you haven't noticed, science over the past two decades has come in for a lot of stick, mainly from an alliance of environmentalists, post-modernists and sociologists who argue, to put it simply, that it is a system of belief that is no more privileged than any other.
Science, they suggest, fits theories to data. It is male-dominated and bears no necessary relationship to reality. Fortunately, most of this nonsense has not trickled down to the classroom. However, science is in danger if we forget what makes science distinctive, namely, the commitment to evidence as the basis of belief.
Scientists have had lots of what now seem crazy ideas - N-rays, the ether and cold fusion to name but a few. But they have all come and gone because they couldn't stand up against the evidence. What is more, the scientific way of thinking now permeates all avenues of rational life. Was the South African referee in the World Cup biased against England? Look at the evidence from the video cameras. Are there weapons of mass destruction in Iraq? Look at what the inspectors have found.
Given that this commitment to evidence is the crowning glory and achievement of science we need to do more to put it to the fore. That is why we at King's, funded by the Nuffield Foundation, have produced a new pack of materials called Ideas, Evidence and Argument in Science (IDEAS) to provide more support for teaching that focuses on the evidence for what might seem an unnatural set of ideas.
Working with teachers we have developed approaches and materials that allow children to consider the arguments for, and against, scientific ideas.
Essentially, we believe (and we have evidence to support this belief) that knowing why the wrong idea is wrong is as important to your learning of science as knowing why the scientific idea is correct.
Take, for instance, the idea that we see object because light enters the eye. Most pupils find this pretty difficult to accept - after all, you "stare daggers at somebody" and look at somebody to see them. Surely vision is active - something comes out of the eye to enable you to see?
But if this was so, wouldn't we be able to see in the dark, you might argue. "Yes," your young sceptic replies, "but that is only because we need light to see by. Once there is light, it triggers seeing." How would you convince him or her they are wrong? How about pointing to the fact that we wear sunglasses to stop light coming into the eye?
It is this kind of debate that our materials aim to promote, because we believe that fostering a commitment to evidence as the basis of belief in science is more important than anything else. Only when we give it its rightful pride of place, and start to interrogate its value and significance, can we transform science into an education in critical thinking.
In so doing, we can help students develop a long-term transferable skill that will have value in all walks of life - something that might be more useful than the current demand of the national curriculum to frog-march them across the scientific landscape.
Jonathan Osborne, Shirley Simon and Sibel Erduran will be presenting their new materials and pack at the ASE meeting on Friday at 11.30am