The busy adult mind forgets the wonderment with which a small child reacts to the most everyday phenomena. It's only when you suddenly have a seven- year-old in the house that you remember when your main interest in life was annoying your family with a tireless stream of impossible questions designed to chart the extent of their knowledge - and patience.
Unless you have an unusually retentive memory, the chances are that you will soon run out of explanations and have to start looking things up. Publishers know this, and the children's department of any bookshop is bursting with attractive titles. Some are actually arranged in the form of questions, but for a more generally useful "book to grow on" you are probably better off with a more conventional science dictionary or encyclopaedia.
The Kingfisher Visual Encyclopaedia of Science (pounds 19.99, pp320) divides into four sections: planet earth, the living world, stars and planets and science and technology. The 10-page index is thorough, with multiple cross-referencing, and the book is illustrated with serviceable coloured drawings. Like a lot of children's non-fiction it tends to assume (not unreasonably) that the child is already interested, so it is not particularly fussed about seducing the casual reader with sexy pictures. It is a little weak on the everyday domestic application of scientific principles, which is a pity, because science badly needs to be made less abstract for children.
Another way of humanising, maybe even glamorising, the world of science would be to include larger panels about the way discoveries are made - Marie Curie poking about in her cauldrons of pitchblende, Fleming and his unwashed petri dishes, etc. Kingfisher doesn't mention either of them.
This may sound trivial, but pure science is in desperate need of a hard sell. At GCSE, the numbers of pupils taking single subjects (physics, biology and chemistry) is in steady decline. Instead, tudents take Combined Science. Without a grounding in the individual sciences, any 16-year-olds opting for A-level get a nasty shock. Indeed, there are reports of universities laying on remedial courses for inadequately-prepared undergraduates. Capture a child's imagination at the right age and this trend could be reversed.
The Oxford Children's A-Z series (pounds 5.99, 64pp) is aimed at younger children who haven't yet broken science down into its constituent A-level subjects. The various titles - Human Body, Science, Technology - all give clear and simple explanations.
The A-Z format is superficially user-friendly, but it can be a little shallow. You might be better off saving your money and giving them a hand with the index of a more ambitious, more detailed work. You may have to face the fact that, until they are old enough to lock themselves into their rooms with headphones and a chemistry set, science books should really be a shared experience. If your long-term memory has binned your O-level physics notes, read through the chosen book yourself so that you can appear confident and knowledgable. Resist any temptation to sound vague, flummoxed or useless. Countless children have been put off maths and science by dozy mums and dads saying, "Don't worry, darling, I could never do maths." Be positive.
Once the child is ready to explore unaided, it will probably enjoy the Oxford Children's Book of Science (a good value pounds 9.99 for 190pp). This uses appealing photographs, ranging from a lady being sawn in half (perception) to a gargantuan weevil emerging triumphantly from a grain of wheat (electron microscope). It also includes a cracking shot of a cheetah peeing against a tree (sheer nosiness). It has the makings of an absorbing read, rather than merely being somewhere to look things up. Though budding astronomers will have to look elsewhere as it leaves the subject out entirely.
Older children will also like the Dorling Kindersley range. This publisher's layout-led approach to the classification of material (designed to occasion the least possible inconvenience when each book is translated) works very well for science.
The Dictionary of Nature and Dictionary of Science (pounds 12.99, 192pp each) are both smallish hardbacks that should provide a colourful supplement to school textbooks. The science volume tackles everything from the proper use of the protractor to the theory of relativity. Almost every section includes a short, interesting panel on the scientists who made historic breakthroughs in each field.
The more cumbersome (and more expensive) Dorling Kindersley Science Encyclopaedia (pounds 29.95, 448pp) is similarly keen to personalise science, and also makes a heroic effort to include ordinary household objects to illustrate scientific principles. Apparently, if you had a big enough bucket you could float the planet Saturn in it. Not many people know that.