The FREE online science and technology book
Want to know why giant ships can float, how your earbuds make music, what graphene is, or how windows can clean themselves? You've come to the right place! Here you'll find simple explanations you can really understand—hurrah!
Hard stuff... made simple!
Explain that Stuff is an online book written by science writer Chris Woodford (author of many popular science books for adults and children). It includes over 400 easy-to-understand articles, richly illustrated with clear artworks and animations, covering how things work, cutting-edge science, cool gadgets, and computers. We take the "pain" from explain and the "tough" out of stuff! There's more information on this website than in your average expensive science book, it's continually updated, and it's completely free to use! Explain that Stuff also helps to support curriculum learning (conventional STEM education and home-schooling).
How to use this site
There are five simple ways to find what you want:
- A-Z index: Browse our articles by name.
- Timeline: Browse articles according to the history of science and technology.
- Random: Discover something new and unexpected.
- Search: Use our Google-powered search engine.
- Teaching guide: Match our articles to a typical home-school curriculum.
What's hot in April 2021?
In the news now...
NASA's just flown a tiny helicopter on Mars. What's so good about rotating wings—and how do they really work?
A British company claims it's found a way to build quantum computers from existing (silicon) computer chips. What exactly is a quantum computer... and why is everyone suddenly talking about them?
Poorer nations want to keep burning fossil fuels to power their economic development, but richer nations want to set tough targets to cut emissions. What's causing the climate crisis... and what's the solution?
A landmark inquiry in the UK made history recently by ruling that air pollution killed a young girl living near a busy road. Why, indoors and out, does dirty air cause an estimated 7–10 million early deaths each year?
The new Perseverance Rover has made a spectacular start to its mission exploring Mars, but it still takes a traditional rocket to put things like this into space. How exactly do rockets work?
These are some more of our classic, ever-popular articles:
- Water pollution: Rivers and seas take a long time to recover from the effects of careless human treatment. What causes pollution and what can we do to stop it?
- Electricity: The most versatile and useful form of energy in our world, electricity is going to become a whole lot more important in future.
- Nanotechnology: Can we build a brave new world just by shuffling atoms and molecules under a microscope?
- Magnetism: One of the first bits of science people studied, magnetism is still just as relevant today in everything from electric cars to body scans at the hospital.
- Gears: Wheels with teeth carved around them can make you go faster or bump up your power—and here's how.
- Batteries: We all need electricity, wherever we happen to be, so thank goodness for batteries—miniature power plants you can carry in your pocket.
- Electric motors: These amazing machines turn electricity and magnetism into movement, powering everything from handheld toothbrushes to bikes, cars, and trains.
- Cloud computing: Why buy yourself an expensive computer or programs to go with it when you can get access to something just as good over the Internet?
- Global warming: Is the planet really heating up? What can we do about it?
What else is on our site?
The articles on our site are divided up into broad topical areas, listed below. We've also given you a rough idea of the kind of questions you're going to find answers to in each section:
- Communications: Why do we bounce telephone calls off satellites? How do cellphones work? What's the difference between digital radio and ordinary radio?
- Computers: How can you make a computer think like a human brain? Who invented the computer—and why on Earth did it take them so long?
- Electricity and electronics: How can you make coffee with a stream of electrons? How can magnets detect burglars in your home?
- Energy: How does wind energy come from the Sun? Is nuclear power safe or not?
- Engineering: What stops a bridge falling over? How come a person can lift more stuff with a crane than with their bare hands?
- Environment: Can we still stop dangerous climate change? What causes air and water pollution and how can the world clean up its act?
- Gadgets: How does a flash memory card store your holiday snaps? Why can a synthesizer mimic any musical instrument that's ever been invented (and even ones that haven't been)?
- Home life: How can you make windows turn dark at the flick of a switch? How does an artificial leg work? If an energy-saving lamp saves energy, how come it still makes exactly the same amount of light?
- Materials: If you had a piece of platinum as big as a man, how much would it be worth? Why doesn't a dry-stone wall fall over? Is it true that glass is a kind of liquid?
- Science: Which part of a candle flame is the hottest? Why does chocolate actually taste good? Where's the best place to sit on a rollercoaster if you want to scare yourself to death?
- Tools, instruments, and measurement: How does an iris scanner recognize your eyes? Why don't fireproof clothes catch fire? Can a robot really learn to play drums?
- Transportation: If a man can't fly, how can a plane fly if it weighs as much as 5000 men? How come we say a wheel reduces friction if it's got a tire that grips the road?
If you like this website...
... you might like my books. My latest one is Breathless: Why Air Pollution Matters and How it Affects You.
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