SCIENCE Two brown-eyed parents can sometimes have a blue-eyed child, and students always want to know how that is possible. The answer lies in the difference between dominant and recessive alleles, one of the most useful ideas in the whole of GCSE genetics. Every trait you inherit is controlled by a pair of alleles, one … Read more
SCIENCE Two students can have completely different eye colours, heights and skin tones, yet still share genes for the exact same conditions without ever showing it. This is where genetics starts to feel confusing, and it all comes down to the difference between genotype and phenotype. Genotype and phenotype sound similar and are easy to … Read more
SCIENCE Look down a microscope at an onion cell and then look at a cheek cell scraped from the inside of your mouth, and you will immediately spot that something is different. Both are living cells, both are eukaryotic, and both carry out the basic functions of life, yet they are clearly built differently. The … Read more
HISTORY Ask a student to name a war and they will usually picture soldiers, battles and front lines. Then mention the Cold War, and the confusion starts. If neither side ever fired a shot at the other directly, was it really a war at all? This confusion is exactly why the difference between Cold War … Read more
GEOGRAPHY Ask a class what deforestation means and almost every hand goes up. Ask what afforestation means and the room usually goes quiet. It is one letter different, but the difference between deforestation and afforestation is actually the difference between destroying a forest and creating one from scratch. This topic comes up constantly in GCSE … Read more
GEOGRAPHY Whenever I introduce this topic in class, I ask students a simple question. Can a country have too many people, or too few? Most assume more people is always a problem. The truth is more interesting, and the difference between overpopulation and underpopulation shows that both too many people and too few people can … Read more
GEOGRAPHY Stand at the base of the Himalayas and then stand at the base of the Sierra Nevada in the United States, and you are looking at two completely different stories written in rock. Both are mountains, but they were not built the same way. The difference between fold mountains and block mountains comes down … Read more
SCIENCE Every living thing on Earth is built from cells, but not all cells are built the same way. I ask my classes this every year: is a bacterium built the same way as a cell in your own body? Almost everyone guesses yes. The real answer is no, and the difference between prokaryotic and … Read more
SCIENCE If you have ever looked at a Biology textbook and seen the letters DNA and RNA sitting next to each other and wondered why there are two different molecules doing what seems like the same job, you are not alone. I have taught this topic to GCSE classes for over a decade, and it … Read more
Science Switch off one light in your house and the others stay on. That is because your home is wired in parallel. But in an old-fashioned string of Christmas lights, if one bulb blows the whole string goes dark. That is because they are wired in series. The difference between series and parallel circuits affects … Read more