# Fifth Period

## First Time Here?

Go to the first strip and
see how it all started!

Join students Sophie, Tomás, Emma, and Marcus during Fifth Period! This STEM comic strip chronicles the exciting and often hilarious adventures of a close-knit group of four friends as they learn about science, technology, engineering, and math from their kooky, inspiring, off-the-wall science teacher, Mr. Kepler. When they're not in class, these kids love to explore the vast world of STEM on their own, launching weather balloons, programming computer games, and cataloging insects, sometimes with unpredictable and highly entertaining results!

Check back on the first and third Friday of every month for a new Fifth Period strip!

March 1, 2013

### A Simple Win for Emma

How was Emma able to throw a much larger and faster snowball than reigning dodgeball champ Marcus? What is it about a catapult that makes it such an effective snowball-launching device? The answer is simple—simple machines!

Simple machines are mechanisms that affect the force of an object—meaning they can change how something moves (or doesn't move)—and there are a few different kinds:

An incline plane is any flat surface at an angle. Moving objects down an incline plane is easier because gravity is helping too.

A wedge is two incline planes fused together that can widen any gap if driven into it. A knife is a very shallow wedge that splits food apart.

A screw is a special kind of incline plane; it’s a very long and thin plane wrapped around a lever. When the lever is turned and pressed down into a surface, the plane wedges underneath the material, keeping the lever from pulling out.

A lever is anything you can pivot on a point (called a fulcrum) to pry something loose or tie something tighter. A crowbar is an example of a lever; you can push down on one end and the other end will push something up.

A wheel & axel is a rounded plane that rotates around a lever, and can carry anything attached to the axel across any distance.

A pulley is essentially a wheel that, instead of moving distances, pulls a cord around itself. It's usually used to raise or lower something on the other end of the cord, like the line on a fishing pole, or the flag on a flagpole.

Try it yourself!

Simple machines are everywhere. How many simple machines can you identify in Emma's catapult?