Suzanne Skufca, Lake County Yard Waste Management & 4-H Program Assistant
One of the nice things about living in northeastern Ohio and having a 90-mile round-trip drive to work is being able to see the seasons change.
The color of tree leaves seems to vary almost daily during the fall, making my travels less monotonous. Watching the transformation of color from emerald green to scarlet, yellow, orange and all points between is like watching a magic show.
The basic science of photosynthesis and why leaves change color can be taught to elementary school-aged children in a lesson called watercolor chromatography.
The easy experiment shows that chlorophyll--the pigment that gives leaves their green color--is accompanied by other pigments. The colors of these pigments only are visible when the process of photosynthesis shuts down because of decreasing amounts of sunlight in the fall.
Coffee filters, water-based markers, and small, clear glass jars, test tubes or other containers are needed. Cut the coffee filter into strips about 2 inches by 6 inches. Have each child use a marker or markers to make a thumb-sized dot 1 inch from the bottom of the paper. Black works particularly well, as does a combination of colors marked on top of each other.
Add just enough water to cover the bottom of the container and gently insert the paper until its bottom edge just touches the water. If the paper is allowed to sit undisturbed for several minutes, the water will wick its way up to the marker dot and continue moving beyond, bringing with it a separation of the colors from the dot. The black color masks the reds, purples and yellows that comprise the marker color, just as xanthophyll (yellow pigment) and carotene (red or orange pigment) in leaves are overshadowed by chlorophyll.
The formation of the reddish, blue or purple pigment anthocyanin also can be discussed during this experiment. Anthocyanin is produced when sugar builds up in leaves because of drought or other environmental stresses. When too much anthocyanin is present, leaves appear purple or red, rather than their normal color.
This experiment can be quite impressive. Combined with a lesson on basic plant science, it provides an inexpensive, simple activity to help children understand "where the green goes" and how leaves change into the beautiful colors seen during the autumn season.
All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.
Keith L. Smith, Associate Vice President for Ag. Adm. and Director, OSU Extension.
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