Plain-English articles on science, history, geography, mathematics, technology and study skills, written for students and checked before publishing.
Rereading and highlighting feel productive but do little. Here are seven study techniques that research shows work better, and how to use them.
Read the articleA year is not exactly 365 days long. Here is why February gets an extra day every four years, and why 1900 skipped it but 2000 did not.
Pi is the ratio of a circle's circumference to its diameter, about 3.14159. Here is why its digits never repeat and how many of them we actually need.
AI powers chatbots, spam filters and video recommendations. Here is what it actually is, how machine learning works, and where it goes wrong.
The most common answer is 195, but it depends on who is counting. Here is where that number comes from and the places that make it tricky.
A peace deal between an English king and his barons in 1215 became a symbol of the rule of law. Here is what the Magna Carta said and why it lasted.
The periodic table looks like a wall of letters, but its layout tells you a lot. Here is how to read each box, the rows and the columns.
Gravity keeps your feet on the ground and the Moon in orbit. Here is what Newton and Einstein each discovered about it, without the heavy math.
Plants turn sunlight, water and carbon dioxide into sugar and oxygen. Here are the two stages of photosynthesis, explained step by step.
Sunlight contains every color, but air molecules scatter blue light far more than red. Here is how that works, and why sunsets turn orange.