 Hi, welcome to the MIX, the teen center at the San Francisco Public Library. My name is Illyana and I'm your host for our STEM Challenge Joseph series. Some of our most amazing librarians are going to share their fun and creative projects and experiments for you to do at home. Today's Challenge Master, you may have seen him around at our techmobile sharing his skills throughout the city. Now, I think you're up for the challenge. Ready? Hello friends, I'm Mr. Joseph and today I will demonstrate how to create a simple windmill made from cardboard. Let's check out the materials. We need circle, make sure it's made out of cardboard, rectangle. We need eight rectangles made out of cardboard, paper tube, pencil, and scissor. To begin, let's start with the circle. Draw four lines that intersect on the middle and are evenly spaced. To achieve that, mark the center. For the first line, the first line will divide the circle into two equal parts. The next line will divide the circle into four equal parts. The third line, evenly space it out with the other line and make sure it intersects the center. Same thing with the final line, evenly space it with the other lines and intersect the center and voila. We have four equally distant lines. Now, make notches on all the lines from the edge towards the center about halfway there. To achieve an evenly cut around the circle, we're going to mark those points. So from the edge, halfway towards the center, and we're just going to eyeball it from the edge towards the center, halfway there, mark again from the edge towards the center, make a mark. Now we're ready to cut. When you're making the notches, make sure you don't pass those marks and we have our notches. Those notches will serve as a connecting point for the rectangles. Now let's go to the rectangles. Similar to the circle, make notches on the short side of the rectangle. Then we're ready to assemble. Align the notches together and gently slide the rectangle. If you're having difficulty inserting them, try widening the notches and make sure they're all tight. And one more thing, make sure all the blades are facing the same way and that the rotation, which is called the pitch, are all the same on each of these blades or rectangles. So in the center, we have the circle, which is called the hub, and around it are blades. And the entire thing is called the propeller. Now we are ready to assemble the windmill. Grab a pencil, insert it on the center, flip it, and now we have a windmill. Well, not yet. Grab your paper tube, insert it behind the axle. That happens. You just reinsert the axle, insert the paper tube, and now we have a windmill. Face it towards the wind and see how it spins. For further challenges, explore other materials and changing the rotation of the blades and see how it affects the speed of your windmill. For further challenges, grab a cup with a string, attach it onto your axle, and test how many coins will it carry. For further challenges, explore other books in your public library about giant windmills that generate electricity. Back to Leanna. Thanks, Joseph. That was great. I learned some geometry, some physics, and I think I love how you can just point it to the wind and watch it move. For more information and tips and tricks on our STEM Challenge yourself series, be sure to visit sspl.org. That's all we have for today. Stay STEM-tastic.