What Makes a Crab Walk Forward and Other Surprises

• How Do Hand Dryers Work?
You’ve probably used one in a public bathroom, those hand dryers that blow warm or cool air. They dry your hands in 10 to 15 seconds. They have sensors that turn them on when your hands block the light.

• Which Crab Walks Forward?
Most crabs walk sideways because of how their legs are built. But the soldier crab is different, it walks forward. These crabs come out when the tide is low and look for food along the edge of the shore.

• How Does an Atomic Bomb Work?
An atomic bomb works through something called nuclear fission. This process releases a huge amount of energy from inside atoms. When neutrons are released, they hit other atoms and cause more reactions, setting off a powerful chain of explosions.

• Why Is It Called the White House?
The U.S. President’s home wasn’t always called the White House. Though it’s always been white, it was first called the “Executive Mansion,” then the “President’s House” or “President’s Palace.” In 1901, President Theodore Roosevelt officially named it the “White House” and used it on his letterhead.

• How Do Traffic Lights Work?
Some traffic lights change colors based on a set time. But busier intersections use computers connected to sensors under the road. These sensors help adjust the timing of the lights in real time to keep traffic moving smoothly.

• What Are the Cliffs of Moher?
Even though their name means “Cliffs of Ruin,” the Cliffs of Moher in western Ireland are stunning. They rise up to 240 meters and stretch for about 8 kilometers along the ocean.

• Who Invented the Piano?
The piano was invented by Bartolomeo Cristofori in Italy. He worked for a wealthy family and created a new kind of instrument based on the harpsichord. But unlike the harpsichord, the piano uses tiny hammers to hit the strings, letting you play both softly and loudly.