A Lesson Plan from the Norfolk Botanical Garden

Hidden Colors

Send questions and comments concerning this lesson to Molly Headden, Norfolk Botanical Garden, Norfolk, VA.

Grade Levels

K - 5

Objectives

Students will be able to:

Standards of Learning

Science
K.1, K.6, K.8, K.9; 1.1, 1.4, 1.6, 1.7; 2.1, 2.4, 2.7; 3.1, 3.8, 3.11; 4.1, 4.4; 5.1, 5.5

Description:

Students will discover the presence of different colors hidden in green leaves by performing a chromatography experiment on chopped green leaves.

Background:

All green plants contain the pigment, chlorophyll, which helps to convert sunlight, water, and carbon dioxide into food for the plant. In addition, many green plants also contain other colors/pigments, some are visible, while others are masked by the dominance of chlorophyll.

Materials:

Procedure

  1. Finely cut or chop the leaves into small pieces and put into the jar.

  2. Add enough nail polish remover to double the depth of the leaves in the jar.

  3. Shake the jar vigorously, and let it stand for about an hour. The solution will turn green from the chlorophyll that is the dominant color.

  4. Cut filters into 1 inch wide strips that are 1 inch longer than the height of the jar.

  5. Put one end of the strip into the solution and fold the other end over the top of the jar.

  6. Let it sit; observe what you see. A green band of color will form at the moist end of the strip and travel up the strip.

Explanation:

The filter paper absorbs the acetone/chlorophyll/pigment solution, and the filter fibers help separate the colors and carry them along in one unit. This process is known as "chromatography", and you have just extracted chlorophyll and possibly other pigments from your leaves. Look closely at the color band. In time, you might see two or more separate lines of green and yellow-green color, which indicate the presence of several types of chlorophyll, as well as oranges and pinks, indicating the presence of other pigments.

Extension and Assessment:

Why Do Leaves Change Color in Autumn?

In Autumn, as the temperature cools and the days get shorter, the leaves' food-making process (photosynthesis) stops. The tree is getting ready to shut down for the winter, and water stops flowing into the leaves. The leaf stem seals off, where it connects to the branch, and the chlorophyll dies. Whatever other pigments are present and dominant become visible as the chlorophyll fades. Eventually the leaves dry up and fall off the tree.

Demonstrate dominance and the presence of chlorophyll and other pigments in leaves, using fall color M&M's (available seasonally in most grocery stores), or use other small, colored candies. Using some of each color, place the items in a bowl. Make sure you group them so the green colored candies or M&M's are green dominant (most abundant). This would represent a green leaf. Again, using some of each color, have students repeat grouping with other colors dominant, to represent other leaf colors that are visible in the fall.

Example:

After completing this lesson and demonstrating an understanding of the concept of dominance and the process of color changes in leaves, the students can eat the experiment!

To learn more about leaves and photosynthesis, plan a visit to Norfolk Botanical Garden. The Garden offers school programs for students in pre-school through 5th grade. You can reach the Education Department at (757) 441-5838 or send us E-Mail!

Web Sites:

Norfolk Botanical Garden http://www.communitylink.org/nbg


Contact person:

Molly Headden
Norfolk Botanical Garden
6700 Azalea Garden Road
Norfolk, VA 23518-5337

(757)441-5838
garden@norfolk.infi.net

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