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Viking Deception, The

Classroom Activity

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Objective
To learn about the chemical pigments of some plant-based dyes.

Materials for each team
  • copy of the "Extracting Colors" student handout (PDF or HTML)
  • one of the following: 1 cup blueberries, 1 cup blackberries, large handful red onion skins, or large handful yellow onion skins
  • goggles
  • hot plate or stove
  • enamel or stainless steel pan (1 liter)
  • large wooden or plastic spoon
  • sieve
  • 1 knee-high nylon stocking (for groups using onion skins)
  • large spouted heat-resistant measuring cup with ml markings
  • cheese cloth for groups using berries (twice the size of jar mouth)
  • 2 pot holders or oven mitts
  • 1 clean, empty jar with lid
  • thin paint brushes, or four 2.5-cm sponge squares
  • white construction paper

Procedure
  1. Ask students to name some different plants or plant parts they think could be used to make dye. Discuss dyes and how inks can be made from natural dyes (see Activity Answer for more information).

  2. In the Middle Ages, scribes often used iron gall ink, a dye-based ink made from galls of oak trees. Many inks are dye-based. In this activity, students will use natural ingredients to make four different dyes (each team makes one dye) and will investigate the pigments responsible for creating the colors in those dyes.

  3. Organize students into teams. Distribute the materials and a copy of the handout to each team. Each team will work together to make a dye from one of the following plant parts: red onion skins, yellow onion skins, blueberries, or blackberries. (If you have the materials available, you may want to have more than one team make the same dye. If multiple teams will be making dye, you might want to have half the class make its dye while the other half does research, and then switch the roles.) Students will predict the color of the dye, learn about the pigment responsible for each color, and investigate the pigment's uses and benefits for humans.

  4. Review the instructions on the handout with students. Have students first predict the color of their dye. Teams will also record the color extracted and the color the dye imparts on paper. Have them research and record the pigment responsible for the color, the pigment's function for the plant, and any uses and benefits the pigment may have for humans. Ask students to save their jar of dye and share it during the class discussion.

  5. To conclude, make a chart on the board that includes: the type of berry or the kind of onion skin used, the dye's color, the color imparted on paper, the pigment's function for the plant, and the potential benefits for people. Compare dye results from the different teams. Which dye had the richest color? What might be some of the reasons for this? Which dyes show up well on paper? What, if any, findings surprised students?

  6. As an extension, have students explore the history of ink and how the process of making ink has changed over time.

Safety Note
Review the proper use of a hot plate with students prior to beginning the activity. Remind students to wear goggles, use potholders when moving hot pans or materials, and work carefully when using the hot plates. Supervise students as they use their hot plates to make their dyes.


Activity Answer

Dyes are soluble matter that impart color. Inks can be made from natural dyes that come from metals or the outer covering of nuts or seeds. Many plant pigments can be extracted and used as dyes, and with additives, made into inks.

The process of ink-making has changed over time. Iron gall inks were used during the 1400s and were made from a mixture of tannic acid and iron salt (often ferrous sulfate). The pigment in iron gall ink does not completely form until it is exposed to air, and the ink is transparent until it is put on parchment or paper. It then darkens and becomes permanent. Gum Arabic, a thickener, increases the flow of the ink and helps it stay on the writing surface. If too acidic, these inks damage paper or parchment.

During the mid-1800s, people started using ammonia-based aniline dyes to make ink. Precursors of today's inks, they were less damaging to parchment and paper. However, these inks tend to fade. Fountain pen inks are often made of aniline dyes plus chemical additives that help increase the flow of ink (ethylene glycol) and prevent bacterial growth (phenols). Other additives make the ink more stable and prevent dyes from solidifying in the pen.

Extracting Colors Pigment Chart


Dye Color in Jar

Color Imparted on Paper

Pigment Name

Function in Plant

Benefit for People

Red Onion

cranberry red

little to none

the flavonoid, anthocyanin

provides color to flower and fruit; color attracts animals for pollination

may act as antioxidant; may also help protect eyes from degenerative diseases

Yellow Onion

golden

little to none

the flavonoid, quercitin

provides color to plant; gives visual cues to pollinators

may act as antioxidant; may also protect against heart disease

Blueberry

deep red

purple

the flavonoid, anthocyanin

gives blueberries their color and provides color to flower and fruit; color attracts animals for pollination

may act as antioxidant; may also help prevent memory loss and disease

Blackberry

deep red

magenta

the flavonoid, anthocyanin

gives blackberries their color and provides color to flower and fruit; color attracts animals for pollination

may act as antioxidant; may also play a role in preventing disease


Links and Books

Web Sites

NOVA Web Site—The Viking Deception
www.pbs.org/nova/vinland/
Find articles, interviews, interactive activities, and resources in this companion Web site to the program.

A Palette for the Palate
www.sciencenews.org/articles/20050108/bob9.asp
Details the health benefits that pigments in fruits, vegetables, and salad greens may provide.

Plant Pigments for Color and Nutrition
www.hort.wisc.edu/usdavcru/simon/publications/97hort0012.html
Describes the function of anthocyanin and quercitin for the plant.

Vikings: The North Atlantic Saga
www.mnh.si.edu/vikings/start.html
Describes the history of the Vikings and sheds light on their culture.

The Vinland Map: Some "Finer Points" of the Debate
www.econ.ohio-state.edu/jhm/arch/vinland/vinland.htm
Examines the scientific evidence regarding the Vinland Map.


Books

Fitzhugh, William W., ed. Vikings: The North Atlantic Saga. Washington DC: National Museum of Natural History, 2000.
Examines the evidence of the Vikings presence in the New World.

Editors of Time-Life Books. What Life Was Like When Longships Sailed: Vikings AD 800 - 1100 Arlington, VA: Time-Life Books, 1998.
Describes the times and conditions under which the Vikings lived.

McIntosh, Jane. The Practical Archaeologist: How We Know What We Know About the Past. New York: Facts on File, 1999.
Provides an understanding of archeology and the work of archeologists.


Standards

The "Extracting Colors" activity aligns with the following National Science Education Standards.

Grades 5-8

Physical Science

Science Standard B:
Physical Science

Properties and changes of properties in matter

  • Chemical elements do not break down during normal laboratory reactions involving such treatments as heating, exposure to electric current, or reaction with acids. There are more than 100 known elements that combine in a multitude of ways to produce compounds, which account for the living and nonliving substances that we encounter.


Classroom Activity Author

Developed by WGBH Educational Outreach staff.

Teacher's Guide
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