 My name is Jim. I'm just one of the librarians you find at San Francisco Public Library's Main Children's Center. So hey, let's do something fun today. We are going to make our own pom-pom catapult. Now have you ever heard of a catapult? Sometimes if you watch a movie that was set long ago in the Middle Ages during the time of knights in shining armor, you might see catapults used to attack castles. And those catapults were huge and they hurled rocks far distances toward castle walls to devastating effect. Well, we're not going to make a big catapult like that. We're going to make a little catapult that will shoot something soft, a pom-pom. Now you can see here in my bowl, I've got a lot of pom-poms. Some fairly decent sized, others a little bit smaller. And our pom-pom catapult should work for all sizes. So now it's time to build. Now I've got all my materials spread out in front of me, everything in my kit. Where do I begin? This is where my instruction sheet comes in. It's got on it all the steps I need to make my pom-pom catapult. And I'm going to use this instruction sheet to make my own. You at home can watch me do it and maybe even follow along if you like. Let's see how we do. Okay. Step one. Use the paint or markers to decorate the popsicle sticks. Now if you want to decorate your pom-pom catapult sticks, you can. Or you can just use plain sticks. I've got some that are different colors and that's just how I happen to buy them. Now you can also use plain popsicle sticks and there's no difference at all. But you can color them if you want to. Step two, prepare the fulcrum. Now the fulcrum is the thing that our catapult is going to bend over so as to give some force to its throw. Now to make the fulcrum we need five popsicle sticks in a stack. One, two, three, four, and there we go. They're all in a stack. Now what do we do? We wrap a rubber band around each end of the stack. Seems simple enough. Let's try it. Here's a rubber band, around it goes, there we are, and now we do the other end. Another rubber band, around and around and around, very good. There we are. This is our fulcrum. So far so good. What's next? We're going to prepare the flinger and just as its name suggests, that's going to be the thing that throws our pom-pom. How do we make the flinger? We stack two popsicle sticks, one, two, stack them just like that, and wrap a rubber band around one end. Okay, there we go. There's one end. Now pull the two popsicle sticks slightly apart, just like, whoops, there we go, just like that, and wedge the fulcrum in between the two. There we go. And then we push it gently down toward the rubber banded end of the flinger. Very carefully I'm going to do that so I don't crack my sticks. Go, go, go, go, go, go, go. Think of that's about as far as I'll try to push it. There we are. Now what do we do? We wrap a rubber band around the entire flinger and fulcrum where they meet, right at the criss-cross. All right? And we wrap it to make an X. So that means this is going to be a little difficult to see but I'll try to make it clear. There's one part of our X and now the other part. Ooh, come here, rubber band, I need to stretch you some more. Go around. That's the way. That's the way. Can I do that a little more? Maybe. I'm going to try it. Don't you break on me, rubber band, though if you do I have plenty more. Is it going to do it? Oops, my big fingers are getting in the way. Push it down a little more. And now you can see I have made my, and I'll push it so it's balanced, just so. And now what do we do? Place the plastic spoon and I've got a few spoons to work with. My plastic spoons are a little fragile. I don't want them to break so I have to be a little careful and have extras. In your kit you should see that you have two to work with. Put the plastic spoon on top of the flinger and wrap two rubber bands around to hold it in place. Got more rubber bands, so that's what I'll do. Around our spoon, I did the easy side first. It's a little loose, let's tighten it up, oops, go around rubber band, there we are. And then I've got to do another one, oops, get down there you. I'm going to push my fulcrum down lower, push my rubber band down lower and now I've got room for a second one. It's easy at first. If it gets a little hard for some of you at home, a big brother could help, a big sister could help, a mom or a dad, aunt or uncle, even grandma or grandpa, that's almost the way I want it. I want it a little tighter. Let's see if I can do that without breaking my rubber band. There we go, that's just right. Now I'll show you what I've got. I've got my fulcrum, my flinger, my spoon tied to the flinger and this is the simple sort of pom-pom catapult. Well now we've got everything ready. Will our catapult work? Let's see. To make it work, you get a pom-pom and I'm going to move our materials out of the way. We hold down the short end of the flinger, put the pom-pom in the bowl of the spoon, press down on the spoon and let go. Are you ready? Pretty cool. It went very high up, didn't it? Let's see if we can try that again from another view so you can see. We put our finger down on the short end of the flinger. We take the pom-pom and put it in the bowl of the spoon. We press down on the spoon and boom, very good. That's the way, that's how it should look. And now we just made the simple version of the pom-pom catapult. Do you want to make another kind? There's another kind we can make that's a little harder, but might even send our pom-pom further. Let's take a look. On the next page of our instruction sheet, we see another design, the pyramid pom-pom catapult. Now this is also with rubber bands and spoons and popsicle sticks. Only this one, there's a few more rubber bandings we have to do. To make the more complicated pyramid pom-pom catapult take some time. So we just decided we'd jump to the finish point. Here's mine. Well, that took a little time to make, but at last I have finished the pyramid pom-pom catapult. Here's what it looks like when it's all ready. Now I'll admit, mine is far from perfect, but it doesn't have to be perfect. It just has to work. Let's see if mine works. Here's a pom-pom, press down on the front, place it in the spoon, whoops, come back here pom-pom. And here we go, boom, whoa, that went far. A little off to the side though, let's see if I can make it go a little more forward. Here we go. Are you ready? Boom. Off to the side again. Well, one more time, third time's the charm. That's a little better. Well, thank you for joining me in making pom-pom catapults. Now why is this STEM? What does this have to do with science, technology, engineering and math? Well, our pom-pom catapults embody Newton's three laws of motion, and they are these. Law number one, we've got it right on our instruction sheet. An object will not change its motion unless a force acts on it. And we know that's true, right? A pom-pom with nothing acting on it stays right where it is in a state of inertia. Law number two, the acceleration of an object depends on the mass of an object and the force applied. What that means is the more force, the faster an object will go and the more mass it has, the more force is going to be needed to move it. And what's our third law? Our third law is simply every action has an equal and opposite reaction. Shall we show what that looks like? Here's a pom-pom. Here's our catapult. Now the action is my pulling back the spoon and the equal and opposite reaction will be the spoon flinging forward and hurling our pom-pom straight out. Here we go. Boom. It looks like I need a little practice. But once again, my name is Jim. Thank you for joining us in making pom-pom catapults.