(SciShow Kids Intro plays)

Jessi: Hey guys, Squeaks and I are making paper airplanes! We're trying to make different kinds and see how high they fly. You want to join us? Just grab some paper and we'll make one together.

Let's start by folding the paper in half, kind of like a hot dog bun. Then, unfold it again and lay it flat. Now, fold down the top two corners. Try to line up each corner so that it reaches all the way to the fold in the middle.

Now stop and take a look. So far you should have a piece of paper that looks like a square at the bottom with two triangles on top, If that's what yours looks like, then let's keep going. Find the outer corner of each triangle and fold the triangle over so that corner touches the middle fold too. Now, close up your paper and flip it over. Fold down each side, just about half way, to make wings.

And you've got a paper airplane. Let's see how it does. That was pretty good, but how does a paper airplane fly? Well, it's all about forces. And in fact, the forces that help paper airplanes glide are the same ones that keep a real airplane flying high in the sky.

A force is something that pushes or pulls on something else, and there are a couple of different forces that act on your paper airplane to make it fly. First, you need a force that creates forward movement. That kind of force is called thrust. In real airplanes, thrust is created by engines which make the jet move forward by taking in a bunch of air and then pushing it out the back really fast.

But our airplane is just made out of paper, no engines, so where are you going to get the thrust? That's right, from you. When you throw a paper airplane, you're providing the thrust by pushing the plane forward. After that initial push, your plane doesn't get any more thrust, it just glides, which is one of the reasons it eventually falls to the ground.

We don't just want our plane to go forward, we want it to float on the air, so we need another force to get our airplane flying high. This one's called lift, and it comes from the shape of the plane. Try making an unfolded piece of paper fly. It's hard. That's because the paper needs sturdy wings in order to fly, but when your airplane's wings slice through the air, they create lift.

As your plane moves, the wings push air out of the way, but the air has to go somewhere, so it quickly moves out of the way by moving up and over the wing, and the faster that air moves over the wing, the less time it has to push down on it, so the air above the wing is pushing on the wing less than the air below it. This force makes the plane go up. A big airplane needs more lift to get off the ground than a small airplane, that's why bigger planes need bigger wings.

Now, the plane that you and I made doesn't have a whole lot of lift because the wings are so thin, so in order to fly this airplane needs a whole lot of thrust, which means you need to throw it hard. But, there are lots of different ways to make paper airplanes, all with different shapes that make the most out of the forces that help them fly. So the next time you're looking for a fun indoor activity, just grab some paper and start folding, and if you come up with an airplane design that you're really proud of, send us a picture. And if you have any questions about anything at all, get an adult to help you leave a comment below or email us and kids@thescishow.com and we'll see you next time.