 If I ask you to separate this mixture of sand and water, will you be able to do that? Well, in other videos we saw that when we tried to mix sand with water, it does not completely mix. And in fact that mixture is called a heterogeneous mixture. There is one more thing that we are observing in this mixture. And if you look closely, you will see that all the heavy sand particles, they are settling at the bottom of the glass. And you see, you see some muddy water at the top. But it does not have those heavy sand particles. So if you want to separate sand and water in this mixture, we can try and let this mixture sit for some time so that all the heavy sand particles, they settle at the bottom. And in fact in this mixture, they have already settled at the bottom. So the first step is done already in this one. And this process of letting the heavy sand particles settle at the bottom is called sedimentation. In fact, in fact this is called a sediment. The next step is we can try and pour the relatively clear but still muddy water from this glass into this glass. Just like this. Okay, now this glass does not have the heavy sand particles because all of them are in this glass. But this one is still muddy, right? It's not entirely clear. At least it's not suitable for drinking anyways. So we will talk about how to further try and remove the small sand particles that are still in this mixture. This process of separating the liquid from the insoluble solid by removing the liquid layer, in this case the water layer at the top from the layer of solid below. This process is called decantation. Here we removed the top layer of water from the insoluble solid below. Sometimes when people drill for oil in the ocean, accidents can happen and oil spills can occur. But there is a way to clean up the oil using the process called decantation. This works because oil is lighter than water and floats through the top, making it easy to separate from the water. Just like how we separated the water with smaller sand particles dissolved in it from the heavier sand particles that were settled at the bottom. Now when there is oil supply in the ocean, scientists and engineers use the same idea of decantation to clean up the water. They use large machines to separate the oil from the water and then dispose of the oil safely. This shows that science really is all around us and we can use the same principles to solve problems both big and small.