To create a leaf chromatograph, tear the leaf into several pieces and place them in the bottom of the glasses, beakers or jars. (Use a different container for each leaf type.) Cover the leaves with alcohol, and cover or close the jar; place in a shallow dish of hot water. Let the leaves soak until the chlorophyll begins to leave them, turning the alcohol dark. Cut a strip from the coffee filter; tape it to a pencil and lay the pencil across the top of the jar so the filter is just touching the alcohol. Let it stand for 10 to 20 minutes.
The alcohol is absorbed by the filter paper, slowly traveling up the paper. The color pigments will gradually separate as the alcohol continues to move upward. You should see a variety of shades in the filter, including bright and dark green, and possibly reds, yellows, oranges and purples. Different leaves will have different pigments. You should be able to predict, based on the pigments in the green leaves, what colors they will turn in the fall. (This is a great project to create in the spring, then revisit in the fall when the leaves begin to change colors.)
Different pigments are seen in the chromatograph because leaves contain a variety of colors in addition to chlorophyll, the green pigment that is most prominent in the spring and summer. Along with chlorophyll, leaves also contain anthocyanin, xanthophyll and carotene. These colors are also found in fruits and vegetables. Anthocyanin creates red and purple foliage and is also found in purple grapes and apples. Carotene causes orange leaves and is found in carrots. Xanthophyll creates yellow tones and is found in egg yolks and bananas. The eastern United States is famous for its brilliant foliage because so many of its trees produce strong anthocyanin pigments, which are responsible for the brightest leaves.
As the season changes from summer to fall, leaf pigmentation changes due to plant biology. Trees absorb water, via the ground, by their roots. They absorb carbon dioxide through the air. These are then turned, using sunlight, into oxygen and glucose. This process is called photosynthesis and is facilitated by the chemical chlorophyll. In the short, dry days of winter, chlorophyll is no longer created, sapping trees of their bright green colors. As the chlorophyll decreases, the bright colors associated with fall become more prominent in the leaves. (Brown leaves are the result of waste buildup in the leaves.)