Innholdsfortegnelse for April 2016 i Click Science and Discovery Magazine for Preschoolers and Young Children

Long, long ago, the world had no wheels. To go places, people walked. Sometimes they had to walk a very long way. To move things, people had to carry them. Sometimes the things were very heavy. After a long time, people learned to tame animals. They trained the animals to carry heavy loads. They built sleds that the animals could drag along the ground. That helped too. Now the animals could move heavier loads. More time passed. People tried using big logs or tree trunks as rollers under the sleds. That made the sled move more easily, but steering was hard. And someone had to keep moving the last log to the front of the sled. At last, someone cut slices from a log and connected them with a rod.…

This is a Formula One racing car. Formula One drivers race their cars around and around a track as fast as 200 miles per hour. Often, the second-place car crosses the finish line just a fraction of a second behind the first-place car. That means the race can be won in less time than it takes you to blink. One reason the cars go so fast is their tires. Race tires are wider and fatter than regular car tires. They’re smoother and softer too. That all helps them stick to the track better, so they can zoom around curves and other cars without crashing. The soft tires wear down quickly, though, especially when they run at superfast speeds. They’re not meant to last through an entire race. So during a…

“RRREERREERERRER– clangclangclangclangclang!” Sam made his loudest siren sound and clanged his silver bell as he raced down the sidewalk. “Goodness, Sam!” called his next-door neighbor, Mrs. Carpenter. “Where’s the fire?” “Zach’s fort!” Sam called back over his shoulder. “He just rang the alarm!” And Sam zoomed away as fast as his legs could pedal. But what was this? Suddenly, Sam wasn’t going fast—he was going bumpety-bumpetybump-bump-THUMP. “Help!” Sam said. He got out of his fire truck and looked. “My wheel came off!” Mrs. Carpenter came hurrying down her front walk, her puppy Goliath at her heels. “What seems to be the problem, Sam?” she asked. “My wheel! I lost my back wheel! My fire truck is broken!” Sam was practically crying, he felt so bad. Mrs. Carpenter gave Sam a…

What You Need  pencils thin cardboard scissors What You Do Cut a pair of circle shapes from the cardboard. You can trace around a can or cup first to make a neat circle. If you use a file folder for your cardboard, you can cut through the front and back of the folder at once to make matching circles. Cut more pairs of shapes. Good shapes to try include squares, triangles, and ovals. Ask an adult to help you poke a small hole in the center of each shape. The shapes will be your wheels. Carefully slide a pencil through the holes in each pair of shapes. The pencil is the wheels’ axle. Now try rolling your wheels. You can give each set a push or let them roll down…

Wheels are great for getting around on the ground. But they roll best on smooth, hard surfaces. How can you travel on soft sand, squishy mud, icy snow, or rocky ridges? Take the Wheels Off A snowboard looks kind of like a skateboard without wheels, and you could think of a sled as a wagon with long, flat runners in place of round wheels. Instead of rolling, they slide quickly and easily over ice and snow. Sleds can be pulled by dogs, horses, or reindeer. Sometimes they’re even used on mud or wet grass. Make Tracks Many construction and farm vehicles have a loop of tracks wrapped around their wheels. When the wheels turn, the tracks do too, moving the trucks forward. The bendy tracks have no trouble pushing over…

What You Need  beans or small pieces of gravel an empty cardboard tube (a stiff one from foil or plastic wrap works best) a sheet of bubble wrap or foam What You Do Scatter the beans over a small, flat area. Gently roll the tube over the beans. Do you feel bumps? Roll the bubble wrap snugly around the tube. You can tape the ends to keep it from shifting. Now roll the tube over the beans. Can you feel a difference? What Happens Smooth tires work best on smooth surfaces. Road bikes, for example, usually have skinnier, slicker tires than mountain bikes. They roll quickly on roads, but the thin tires can sink into dirt or gravel. The fat, knobby tires of a mountain bike grip the ground better,…