 Hi, my name is Eliana and I'm a librarian at the San Francisco Public Library. This summer, our youth engaged in library leadership teen interns created over 20 short videos using general household items that explore the variety of concepts found in science, technology, engineering, and math. This month will be a total teen takeover where we'll be airing videos every week day at 3 p.m. You can find these videos on the San Francisco Public Library's YouTube channel, specifically the STEM Challenge Yourself playlist. Also on Facebook and Instagram by visiting at SF Public Library. To see the makers behind the scenes, be sure to visit at themix.sfpl on Instagram for post featuring our Yale interns and what they like to do when they're not yelling. Our kickoff episodes focus on molecule manipulation and creating crystals with super cooling. Also, some challenges recommend adult supervision. So watch along, take notes, and try this challenge out. We'd love to hear how it went. Good luck! Hi, I'm Annabelle and I'm part of the San Francisco Public Library's Yale program. This video is going to be about the states of matter and how they work. You'll see how to make a cloud in a bottle, demonstrating how water evaporates into clouds in real life. Let's experiment. We need a large jar of ice, hot water, matches, a thin tray, and ice. The first thing you'll want to do is fill your tray with ice. Next, fill the jar with hot water. It does need to be boiling, warm tap water, it still works. Stir the water around with a spoon. You'll find out why we did this later. Next, light a match, blow it out after a few seconds, and toss it into the jar. Immediately put the tray with the ice on the jar covering the top. Look for a misty cloud forming near the top of the jar. If it's hard to see, you can lift the tray a little bit and watch the cloud escape. The cloud forms because the water vapor from the hot water condenses onto the smoke particles from the match. When we stirred the hot water, we helped the water evaporate into the air in the jar. When we threw the match in the jar, it let out smoke particles. After the tray is covering the jar, the water is both trapped and cooled down. The temperature makes the water go back to being liquid, and it sticks onto the smoke particles. In real life, clouds work the same way. Water is evaporated from the ground when the temperature rises, and it sticks to things like smoke and dust in the air to form clouds. When it collects enough water, it falls away in the form of rain. The water's state of matter is determined by how much energy is put into the system. This visual is sniffle-flying water molecules and representing them as circles. When the water is frozen, there isn't a lot of energy in the system. The molecules are all packed together, barely moving. Since energy wants to distribute as much as possible, the ice melts by drawing into heat in the form of energy from the air around it. The ice is warming up to become water, and the air around it is cooling down. When the water is in the liquid state, it has more energy. It's moving a lot more than it was when it was frozen, but it's still connected to the molecules around it, making it flow. Water happens to be liquid at room temperature, so that's why we think of it as a default state. When water is in the gaseous state, it holds a lot more energy. They're not held together anymore, and they're all moving around a lot more. Connecting this back to the experiment, we had water in all three states. The hot water is liquid, and since it was so hot, it held a lot of energy. When we stirred it, we added even more movement to it, and encouraged it to evaporate a little more. Then we covered the jar with the ice, and as the ice melted, it drew the heat from the air below it, cooling down the water vapor. The ice is moving from solid to liquid, and the vapor is moving from gas to liquid. Thank you so much for watching! I hope you learned a little bit about how the states of matter work, and that you have a chance to try out the cloud in a jar experiment. Thanks for watching today's episode of our STEM Challenge Yourself Teen Takeover. Be sure to check back every weekday at 3pm for new videos and challenges. Don't forget, you can visit sfpl.org slash STEM challenge for the list of all videos with materials and objectives. Stay Stem-Tastic!