Blog
Why is a rainbow curved? Why does a magnet stick to the fridge but not to wood? Short, sourced, clear articles.
Picture a ruler who busies himself with stars instead of war and has a giant observing instrument built near his palace. We tell the story of the observatory Ulugh Beg founded in Samarkand, his star catalogue and his tragic end.
7 min read
What is pi, where does 3.14 come from, and why do its digits never end? We explain this ratio between a circle's circumference and its diameter, Archimedes' method, the 22/7 misconception, and how to measure pi at home with a piece of string.
7 min read
Do rays come out of our eyes, or does light come into them? A thousand years ago Ibn al-Haytham answered this question not by argument but with dark-room experiments. We look at his place in the history of optics and the experimental method.
7 min read
Why do fractions feel so hard? With examples, we look at where pizza slices fall short, the power of the number line, common mistakes, and ways to make adding, comparing and dividing fractions meaningful.
11 min read
Why does sweating cool us down, why does cologne feel cold, and why does water stay cool in a clay jug? We explain the states of matter, changes of state and the secret of evaporative cooling through the motion of molecules.
7 min read
About 2,200 years ago, without going into space, Eratosthenes of Alexandria used nothing but shadows and geometry to calculate the Earth's circumference with surprising closeness. We work through his method step by step.
7 min read
Why does a cucumber shrivel in salt water, and why does a raisin swell in water? Using Turkish pickles as our example, we explain what osmosis is, how the cell membrane lets some things through, and why drinking seawater makes you thirstier.
7 min read
Why does the Moon change shape every night? We show that the phases come from our viewing angle, not Earth's shadow, and explain the order of crescent, quarter and full moon and moonrise times with a simple experiment.
10 min read
The word 'algorithm', at the heart of every computer, comes from the name of a mathematician who lived in 9th-century Baghdad. We tell the story of al-Khwarizmi's life, the birth of algebra and how his name travelled from Latin to the present day.
7 min read
Does the mass of a huge tree come from the soil or from the air? We explain what photosynthesis is, its equation, why leaves are green and the most common misconceptions, with a floating leaf-disc experiment you can try at home.
8 min read
Is summer hot because we are closer to the Sun? No. The real cause of the seasons is Earth's axial tilt. We explain the angle of sunlight, day length and the common misconception with examples.
10 min read
Sunlight is white, so why is the sky blue and the sunset red? We explain Rayleigh scattering step by step, why we see blue rather than violet, and why clouds stay white.
10 min read