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In this podcast, John English visits the Reeves ASK Science Center, where Explainer Greer McGettrick shows us how to do a Fall-related science project. Listen to the podcast and follow along with these step-by step photos.

En este podcast, Luz Vargas enseña cómo a haga un proyecto de la ciencia sobre otoño. Escuche el podcast y siga junto con estas fotos.

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Why leaves change color in the fall

Today we are going to show how to separate the pigments of fall leaves.

Here are the materials you will need:

4 leaves each a different color. 4 baby food jars, or small glasses Coffee filters or blotting paper Isopropyl Rubbing alcohol or nail polish remover Aluminum foil 1 Shallow pan Hot tap water Tape Pen Clock or timer Mortar and pestle (or a rock and hard surface to grind leaves on)

We will be using isopropyl alcohol and hot water; both can be dangerous, so it is very important to have an adult help you.

Leaves produce pigments. We produce pigments that give our skin color. The pigments in leaves are chlorophyll, carotene and anthocyanins. These pigments make the colors green, yellow, orange, red and brown.

Chlorophyll is very important to the tree, it absorbs sunlight and a chemical we breathe out called carbon dioxide. It then turns into sugar (also known as glucose) for the plant as food. This process is called photosynthesis.

But photosynthesis only happens when the weather is warm and the days are long (like in the Spring and Summer.) In Fall and Winter there are shorter days and the leaves do not have enough sunlight to produce chlorophyll. This slows or stops photosynthesis from taking place. The chlorophyll fades and all that is left in the leaf is the other pigments, carotene and anthocyanin, leaving the leaf the colors of fall.

Some leaves do not change color in the fall. Pine trees cover their needle in wax to protect them from the cold. Other trees can still produce chlorophyll even if there is less sunlight in the fall or winter.