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What do you know about Chlorophyll?

What’s the first thing that comes to mind when someone says, autumn?  If you’re anything like us, it’s the gorgeous colors of the leaves in the trees.  But, how does that happen?  Where does that color come from?  Investigate the secrets of fall this year by conducting a science experiment that reveals the colors leaves turn in the autumn and explores the science behind this gorgeous transformation that occurs every year.

Discover the colors of autumn with this STEM challenge that explores leaf science and chlorophyll!

 Background Information:

  • During the spring and summer the leaves serve as factories where most of the foods necessary for the tree’s growth are manufactured. This food-making process takes place in the leaf in numerous cells containing chlorophyll, which gives the leaf its green color. This extraordinary chemical absorbs energy from sunlight that is used to transform carbon dioxide and water to carbohydrates, such as sugars and starch.
  • Along with the green pigments are yellow to orange pigments, carotenes and xanthophyll pigments which, for example, give the orange color to a carrot. Most of the year these colors are masked by great amounts of green.
  • In the fall, changes in the length of daylight and in temperature cause the leaves stop their food-making process. The chlorophyll breaks down, the green color disappears, and the yellow to orange colors become visible.
  • Other chemical reactions may occur, which form additional colors through the development of red anthocyanin pigments. Some mixtures give rise to the reddish and purplish fall colors of trees such as dogwoods and sumacs, while others give the sugar maple its brilliant orange. Autumn foliage of some trees show only yellow colors. Others, like many oaks, display mostly browns. All these colors are due to the mixing of varying amounts of the chlorophyll residue and other pigments in the leaf during the fall season..

The Challenge:

Using a collection of leaves from different trees, discover how chlorophyll changes the colors of leaves.

The Materials:

  • Different colored leaves (We used a green, green & red, yellow, and brown leaves)
  • Pot of boiling water (adults only)
  • Rubbing alcohol
  • Small containers with lids
  • Tongs

The Experiment:

  • Place leaves in a boiling pot of water for 5 minutes.
  • While the leaves are boiling, fill up small containers with rubbing alcohol.
  • When the five minutes are up, use the tongs to remove the leaves and place each one in the rubbing alcohol containers. Make sure to sort by color if you are using multiple leaves.
  • Observe the changes to the color of the alcohol.
  • Come back throughout the day and check to see if the alcohol has changed color.
  • Send us your results.


Once you have finished this challenge, email our Youth Services Manager, Gina Knowlton,  Please include your first and last name, a picture of your experiment, and tell us what colors you discovered.

We will post any entrants experiments to our Facebook page on Thursday, October 15th!