What color is this leaf?

Objectives:

  1. Students will identify the many colors in leaves by making chromatography strips.
  2. Students will change their ideas about seasonal changes through guided scientific inquiry.

Materials:

  1. variety of leaves (some fall if possible)
  2. fresh spinach and beet leaves
  3. porcelain or stone coffee mugs
  4. smooth round rocks
  5. spoons
  6. acetone fingernail polish remover
  7. scissors
  8. round coffee filters
  9. Q-tips with end cut off
  10. measuring cup
  11. isopropyl alcohol
  12. clear plastic cups
  13. tape
  14. ruler
  15. pencil

Vocabulary

  1. pigment- coloring material in animals, plants, or paint.
  2. chromatography- a method scientists use to separate materials that are different.

Procedure

  1. Have students rub acetone on a leaf with Q-tip. (Color should not come off)
  2. Ask the students why acetone nail polish remover will remove nail polish but not the color of a leaf.
  3. If students can not come up with a method for removing the color, teacher should suggest breaking the leaf.
  4. Students break up several pieces of one kind of leaf and put them in a mug.
  5. Grind with the rock.
  6. Add one spoonful of the acetone (try to use clear so students don’t think the color of the polish makes a difference)
  7. Students should continue to grind the leaves until some color has entered the acetone solution.
  8. Let sit for 1-2 minutes.
  9. Have students use scissors to cut the coffee filter into a 2” x 8” rectangle.
  10. Mark WITH PENCIL a line one inch from the end of the filter.
  11. Use the Q-tip to place one drop of the liquid on the filter paper at the line (liquid from more than one type of leaf can be used on one filter paper if students are very careful and if the drops are all lebeled).
  12. Let dry.
  13. Repeat steps 11. and 12. several times.
  14. Students should obtain a clear plastic cup with ¼ cup alcohol from the teacher.
  15. WITHOUT submerging the colored spot, students should carefully place the strip in the alcohol with the colored spot close to the alcohol.
  16. Use paper clips to secure the strip to the cur if necessary.
  17. Observe (possible for one hour) and then record observations in science journal.
  18. Remove the filter paper strips from the cup and allow them to dry.
  19. Tape the strip in student journal next to observations.
  20. Have students discuss the different colors that separated.
  21. Try to get students to relate those colors to what colors the types of plants used would produce in the fall. (Which would appear first? (last on paper) Last? (first on paper).