Why Do Some Leaves Change Color_

Hi, I am Jared. Welcome to Fun Science Demos. Today I am surrounded by leaves. Well, these leaves, if you look at them, tell a very interesting story. Take a look. Do you have an idea of what story they actually tell? Well, where I live, most of the trees are going through this interesting change. Their leaves, most of their leaves, are changing from this nice green to all of these different wonderful colors. Reds and yellows and oranges and browns and all of them mix in between. So the question I have is, why do those leaves change colors? Scientists like to ask a lot of questions. So let us ask a question. When do these leaves start to change colors? Through science we have discovered that these leaves start to change colors when there is less hours of sunlight during the day. The amount of sunlight during the day is what is key to these leaves changing colors. So why? So let us ask another question. Why is sunlight so important to leaves? Well, through science we have discovered that there is a secret ingredient in these leaves, and that secret ingredient uses sunlight to do some really amazing things. Let us see if we can take a closer look at that secret ingredient found in leaves. Now, through science we have discovered that that secret ingredient is only found in green leaves. So to take a closer look at that secret ingredient, I need some green leaves, I need some rubbing alcohol, I need a paper towel, and I need a blender. Now we are going to put science to action. I am going to dump some rubbing alcohol into the blender. You can see that rubbing alcohol is clear. I can see right through it. Next, I need to take some leaves and just tear them up into the blender. The blender is going to do most of the work, and you can leave the stems out. Now, I am ready to blend the leaves. Take a close look and watch what happens to the clear rubbing alcohol. The blender is chopping the leaves up into small little bits. I am going to stop the blender shortly so we can take a closer look and see what is happening. So I finished blending my leaves and my rubbing alcohol. Take a look. What do you notice? Well, I notice that the green stuff in those leaves has now colored the rubbing alcohol. The rubbing alcohol is now green. That is a lot of green stuff in those leaves. To take an even closer look at the secret ingredient in green leaves, we need to pour the rubbing alcohol from the blender to a cup. We also need some paper towel strips. All I am going to do is tear the paper towel into little strips. You can cut them. You can tear them. It does not matter. Now I am ready to take a closer look at the secret ingredient in green leaves. So what color do you see in the cup? Well, obviously it is green. That secret ingredient in those green leaves, guess what? It is green. To take an even closer look, we need to take this paper towel strip and we are going to put it in the cup. Put it right in the liquid. I like to bend the paper towel so it hangs on the cup. What is going to happen? That rubbing alcohol with the green is going to rise up through the paper towel and we are going to give it some time. So I am holding two strips of paper towel that I let sit overnight. I have also let them dry out. Let us zoom in and take a closer look and really look at what happened to our paper towel. Take a look at our paper towel. What do you see? Well, I see two colors. I see green, but I also see yellow. What does that mean? Well, that means that in my green rubbing alcohol, my green mixture, there must be some yellow color in there too. Well, why cannot I see it? I cannot see it because there is so much of that green secret ingredient. But when I let it filter through the paper towel, the yellow comes out. Where have I seen those two colors before? Green, yellow. Green, yellow. What is happening is that green secret ingredient is in this leaf. And when that green secret ingredient goes away, the yellow is left behind. So all of these leaves used to have the green secret ingredient. But the tree actually started to pull that green secret ingredient back in so all of these colors could show through. Now, when did that happen? Well, the tree started pulling that green secret ingredient back in when there was less hours of sunlight during the day. So what is this green secret ingredient and what does it do with sunlight? Scientists call that secret ingredient in leaves chlorophyll. And chlorophyll works with sunlight to help make that tree grow and help make that tree make food. Think about that. All the green stuff in this leaf, that secret ingredient, is called chlorophyll. And that chlorophyll works with the sunlight to give the tree energy to grow and energy to make food. Now, scientists have a really neat name for that whole big process. It sounds scary, but it is really not when you break it apart. Scientists call it photosynthesis. Photo means light. Synthesis means to make. The tree uses light and chlorophyll to make food and get energy. That green secret ingredient chlorophyll is so important that trees want to draw it inside and save it when there is not enough sunlight. So when there is not enough sunlight, the green stuff goes back into the tree, the colors show through, and then they save that green stuff inside for next year when the tree can grow new leaves and get more chlorophyll to work with the sunlight to have more energy to grow more food. And the cycle goes on and on around. Science is so cool. If you want to learn more, check out our links in the video description. Thanks for watching.