 Hi, my name is Ileana and I'm a librarian at the San Francisco Public Library. I'm here in the MIX, the Teen Center, and we are here to bring you the STEM Challenge Yourself series, where our phenomenal librarians will walk you through some science experiments that you can do at home. I'm extra excited about today's challenge because whenever you're in a celebratory mood, you can break it out. I'll let the Challenge Master walk you through the science and the project. I think you're ready. Hi, everyone. My name is Davey. I'm a librarian here at the San Francisco Public Library. Believe it or not, it's almost the 4th of July already and California's in yet another drought. This has me wondering, how can I make my own fireworks without any fire? Well, today we're going to find out by making fireworks in a jar. Now, to do this experiment, we're only going to need a few things, all right? First thing we're going to need is a jar or a glass. Then we're going to need some warm water. Next we'll need a little vegetable oil. Finally, we're going to need some food coloring to make our fireworks and a fork to mix them up. So let's go ahead and get started. All right. The first thing we're going to do is we're going to measure out three to four tablespoons of our oil and place it into our dish. I'm going to go ahead and do three of them. Very nice. All right. Next we are going to make our fireworks, all right? I'm going to use food coloring. I'm just going to use one or two drops of each of my colors. As you'll notice as I'm dropping them in, the food coloring does not mix in with the oil. All right. I've got a couple of drops of our food coloring and now I'm just going to mix them up with a fork a little bit. You'll notice they break down into smaller spheres of color, but they don't mix into the oil. All right. Next I need my warm water, all right? And I'm going to go ahead and pour that into my jar. All right. Now we are going to make our fireworks by carefully pouring our oil food coloring mixture into the water. Wonderful. All right. Now we're going to observe what happens. I see that the oil and the water didn't mix and I see that my food coloring is hanging out on top, but oh, look, there is my very first set of fireworks. Now as the food coloring, which is more dense than the oil, slowly seeps through, it eventually makes it into the water where it makes these, oh, really, really, really cool looking fireworks. Oh man, I see blue, I see green, I see red and yellow and it's really taking off. Well, what is going on in this experiment? Well, this experiment has to do with density. Now all matter, all the stuff in the universe is made up of these tiny little parts called atoms. Atoms are the smallest bits of things that they can be broken down into. If you've heard of things like hydrogen or oxygen or even gold, these are all types of atoms. Now atoms come together to form something called a molecule. If you've heard of water, H2O, that is a molecule. Density measures how packed together molecules are inside of things. So something that has a lot of molecules packed together like a rock will be more dense than something that has less molecules, more spread out, like water or air. Now our fireworks are made of oil, water, and food coloring. Let's observe. Which one is the most dense and which one is the least? Well, our oil is floating on top. So that makes oil a little less dense than water, all right? Food coloring, on the other hand, is basically water with a little bit of extra stuff mixed in. So it's a little more dense. So it floats down. And as it slowly goes through the water, it will eventually sink. So these really cool fireworks won't last forever. Eventually because the food coloring is a little more dense, it's going to sink all the way to the bottom of our jar. But this is it. These are our fireworks and they're looking really good. If you want to mix it up from here, you can take it to another level with your fireworks, all right? Instead of putting the food coloring in the oil, why not try dropping it into the jar? You think you can still make a firework that way? What about trying to make different patterns? That could be a fun thing to do. Or mix in other liquids with other densities. I'm suddenly starting thinking, wouldn't it be fun to have some chia seeds floating in there? I wonder what would happen to my fireworks. Thank you for joining me on this STEM challenge. I'm going to give it back to you, Leona. Wow, Davie. Thanks for sharing the sparkle behind the science. I love that you can learn about density by using just a couple of ingredients. For more information about this STEM challenge and resource list to help you do more STEM challenges, be sure to visit sfpl.org slash STEM challenge. Be sure to make your fireworks in the jar and share it with us on social media. Stay STEM-tastic.