The beautiful colors we experience as autumn approaches are something we look forward to every year.  Reds, oranges, and yellows mix with the summer greens to let us know colder temperatures are here.  

Why Do Leaves Change Color in the Fall?

Why do a leaves colors change?  It has to do to with chlorophyll, the part of the plant that makes a plant’s leaves green.  Chlorophyll also plays a major part in photosynthesis, which is the ability of the plant to use sunlight to make its own food.  During the warm seasons, chlorophyll absorbs sunlight, which causes a chemical reaction to make glucose, which feeds a plant.

Pigments You Don’t Normally See

A tree’s leaves have pigments in them that we can’t observe when chlorophyll is present. 

 In the fall, In the fall, colder temperatures and the earth’s tilt away from the sun causes the chlorophyll to break down. Plants make colored pigments at the end of the summer season; we observe them as the chlorophyll deteriorates. The bright yellows in an oak tree contain a pigment called xanthophyll and the dark red of a maple contains anthocyanin.  These trees display a brilliantly colored picture.

What Is Leaf Chromatography?

A fun seasonal experiment to perform is leaf chromatography.  Chromatography means to separate a mixture into its various components.  In this experiment, we’ll see breakdown of a leaf’s colors.

Materials

• Leaves from 2 different trees
• 2 glasses (1 for each leaf)
• Isopropyl alcohol
• Plastic wrap
• Morter and pestle (or something to grind your leaves into tiny pieces)
• Ruler
• Scissors
• Pen
• Chromatography paper strips (coffee filters will work almost as well)

Activity

Make a hypothesis:  What do you think you’ll see during this activity?

• Prepare your paper by cutting it into 2 strips of about 2-3 cm wide and 6-10 cm long. You’ll want the pieces long enough to fold over the edge of each glass.
• Tear your first leaf into tiny pieces. Grind the pieces with a mortar and pestle to a powder. Add the powder to 1 glass.
• Do the same with the second leaf.
• Add a small amount of isopropyl alcohol to your leaf glasses. You’ll want just enough to cover your mixture.
• Dip just the end of one of the pieces of chromatography paper in the first mixture, folding it over the side of your glass to secure it. Cover your glass with plastic wrap.
• Do the same with the second glass.
• Let your glasses set for 1-2 days (you can speed this process up by setting your glasses in a pan of warm water).
• Sketch your findings.

Draw a conclusion:  Were you able to separate the colors of the leaf’s pigments?  How long did it take? Was your hypothesis correct?  

Why Leaf Chromatography Is a Perfect Seasonal Science Activity

Chromatography is a great way to see a breakdown of the pigments on display in an autumn leaf!  This simple experiment gives kids a chance to observe and record what they have learned. Connect art, creative writing and nature study when you incorporate drawing and journaling into the activity!

Sign up for our monthly newsletter above and get a free printable to use with this experiment, plus other free resources to help you have some fun this fall as you add some science into your day!