 Hi, my name is Illiana, and I'm a librarian at the San Francisco Public Library. Welcome to the MIX, the Teen Center. I am your host for the STEM Challenge Yourself series, where our extraordinary librarians walk you through some projects that you could do at home. Today you're going to learn a little bit about chemistry in a very, very tactile and messy way. But I'm going to let our Challenge Master teach you how to do it. Ready? Hi guys, I'm librarian Kimberly. Today we're going to be making some bubble dough. I've also heard it called dish soap slime. Not exactly slime, not exactly oobleck, not exactly silly putty, not exactly Play-Doh. So what is it? Well, today we're going to be doing some chemistry, which is a branch of science that studies things like liquids and solids. And we're going to investigate whether bubble dough is a liquid or a solid. 300 years ago, a scientist named Sir Isaac Newton identified the ideal properties of liquids. Liquids like water are not rigid. They move around and they have an easy flow. Solids like an ice cube are rigid. They're in a fixed state and they do not flow. So will bubble dough end up being a liquid or a solid? What do you predict? Today you're only going to need two ingredients for your experiment. We're going to need some cornstarch and some dish soap. So your bubble dough is going to end up being the color of your dish soap. So since I'm using a green dish soap, my bubble dough is going to end up being a greenish color. But if you use a different colored dish soap, your bubble dough will end up being a different color. You can also use liquid hand soap if you don't have dish soap or even shampoo will work. You're also going to need a large bowl, a third of a cup measuring cup, one tablespoon, and a spoon for stirring. You're also going to get a little messy during this experiment. So make sure you have adult permission and you might want to have a wet towel nearby just to clean up any spills or messes. So are you ready to get started? We're going to start with our cornstarch. And we're going to measure this out over our bowl so that we don't make a big mess. And you don't have to be super precise. That's good. And just dump that into your bowl. And then I'm going to put a little bit extra in there just in case I need some later. Because once my hands get messy, it's going to get harder to get the cornstarch out. Now we're ready for our dish soap. We're going to start with two tablespoons of the dish soap. All right. Now we're going to stir that with our spoon. There we go. And just mix that all together until your ingredients are combined. So depending on your ingredients and what climate you're in, you might need anywhere from two to four tablespoons of dish soap. So here we've only used two and you can see it's pretty dry. So we're going to need to add some more. We might not need a whole extra tablespoon. So I'm going to start with half of a tablespoon and add that to my solution. And we'll give that a stir. And now we're ready to start getting messy. So let's get our hands in there. You want to combine it with your hands just to help it all bind together. Starting to come together there. A little pretty dry. I think I'm going to need. I'm going to add another half a tablespoon and just do a half at a time. So it's harder to go back than it is to go far. Keep mixing it together with your fingers. There we go. So you're a big sticky mess. All right. So keep combining it with your hands. There you go. You can see why it gets very messy here. There we go. Starting to come together. All right. So knead it with your hands. You can knead it. You can mold it into different shapes. Can you break it? What happens if you hold it up high and then let go of it? Isn't that weird? Observe your bubble dough. What does it look like? What does it feel like? It's a weird texture, isn't it? What does it smell like? There's all kinds of different dish soaps you might have used. So it'll smell like whatever your dish soap smells like. Now don't taste it. So although cornstarch is edible, it's used in gravies and sauces and even pie filling. But you don't want to be eating dish soap. So keep experimenting. You only have two ingredients, cornstarch and dish soap. So you can't go too wrong. If it's too dry, add more dish soap. If it's too wet, add more cornstarch. And this is the consistency you are looking for. So what do you think? Is bubble dough a liquid or a solid? Well, it was actually a trick question. Some liquids, like water, do flow freely. But our bubble dough acts a little bit different. When you give it pressure, it acts like a solid. But then when you let it flow freely, it acts more like a liquid. So not all liquids follow Newtonian principles for ideal liquids. Some of them just act kind of weird. And those are things like slime and oobleck and, you got it, bubble dough. They're called non-Newtonian fluids. And they're just a different substance altogether. So what was happening in our chemical reaction? Well, the dish soap and the cornstarch act like magnets and they stick together. The dish soap has a head and a tail end of their molecules. The tail end likes to be attracted to things like oils and fats, which is why it works so well for washing dishes. But it's also attracted to this long carbon train that the cornstarch has. As more and more of the dish soap attached to the corn starch, your solution gets thicker and thicker until it turns into a different substance altogether, the non-Newtonian fluid bubble dough. Thanks so much for experimenting with me. See you next time. And back to Ileana. Wow, Kimberly, that was pretty cool that you could do all that with just two ingredients. Be sure to get messy, but clean up after yourself. And for more information about this challenge and others, find out tips and tricks at sfpl.org slash STEM challenge. Keep experimenting and stay STEM-tastic.