An algebraic equation contains one or more letters in it. Each letter in the equation is called a variable. A variable can change in value. We guess at different values for each letter until our ...

Simultaneous equations are two linear equations that can be solved using bar models. By remembering that the same letter will always have the same value we can work out the missing values. To solve ...

A version of this story appears in the September 2020 issue of National Geographic magazine. Philadelphia detected its first case of a deadly, fast-spreading strain of influenza on September 17, 1918.

Long before anyone knew of SARS-CoV-2, a small band of government and university scientists uncovered a prototypical key that unlocked life-saving immunizations. The SARS-CoV-2 spike protein, which ...

In a striking departure from the traditional cosy English mystery, a new adaptation of Agatha Christie’s beloved characters, Tommy and Tuppence, is set to bring the iconic sleuths into the 21st ...

2026 update to the user-friendly photo editor brings even more AI tools, including the ability to create images from text prompt. The update for 2026 is not just about fancy AI features, you’ll also ...