Back to Teachers Home

Ice Mummies -- Frozen in Heaven

Classroom Activities

Objective
To investigate the rate of microbial growth at different temperatures.

• copy of "This Is Rotten" student handout (HTML)
• 3 small Petri dishes
• 1 small packet unflavored gelatin
• small saucepan
• 1/2 cup water
• 2 teaspoons sugar
• tape
• one food sample (such as tofu/bean curd, strawberries, or bread)
• knife for slicing
• refrigerator and freezer

1. Organize students into groups and distribute materials and student handouts. With students, determine what food they would like to use in the experiment, and assign each group one sample to study (samples might include tofu/ bean curd, strawberries or bread). Also discuss how students will quantify and measure microbial growth rates.

2. Have students predict what will happen to their sample at various temperatures. Then have them prepare the medium that will contain their samples. Important: Discuss with students that their medium may not be completely sterile and that what grows in it might not be directly related to their samples. (As an extension, you may have students repeat the experiment using sterile techniques and compare the results with the first experiment.)

3. The containers should be left in a dark place at room temperature. Once microorganisms have begun to grow, have students record the temperature for the refrigerator, freezer, and cupboard or drawer, and then place one of their samples in each environment.

4. Have students check their samples every few days for two weeks and record their observations.

5. To conclude, ask students to describe the differences in the rate of microbial growth among the samples in the different environments, and possible reasons for those differences. Then discuss with students what might be responsible for promoting or inhibiting growth in each specimen.

6. As an extension, students could examine their final products unaided, with a hand-held magnifying glass, and then with a 10x (or stronger) microscope and describe what they see.

Microbial growth will continue to flourish at room temperature, will be slower in the refrigerator, and will be slowed to the extent that growth may not be visible within the given time in the freezer. The microorganisms that have grown in each sample will probably include bacteria, which are single-celled organisms that feed on waste materials and dead organisms. Mold may also be evident.

Books

Lauber, Patricia. Painters of the Cave. Washington, D.C.: National Geographic Society, 1998.
Provides an introduction to Ice Age people. Text and images depict artifacts and cave paintings left behind by ancestors of modern humans.

Moseley, Michael Edward. The Incas and Their Ancestors: The Archaeology of Peru. New York, NY: Thames and Hudson, 1992.
Provides the prehistory of the Andean region, including a thorough summary of Inca civilization.

Articles

Reinhard, Johan. "Research Update: New Inca Mummies." National Geographic (July 1998): 128-135.
Describes the December 1997 return of Reinhard and his crew of archeologists to the summit of Pichu Pichu in the Peruvian Andes to discover more human ritual remains, gold figurines and other evidence of the Inca heritage.

Web Sites

NOVA Online—Ice Mummies
http://www.pbs.org/nova/icemummies/
This Web site, originally a NOVA/PBS Online Adventure launched in Fall 1996, will provide Updated information about the archeological expeditions that discovered three different ice mummies.

Mummies 101
http://www.pbs.org/nova/chinamum/mummies101.html
Contains information about mummification, specifically the practices of the Aleut. Note: This site contains some graphic photos. Preview first to determine its appropriateness for your students.

Ice Treasures of the Inca
http://www.nationalgeographic.com/features/96/mummy/index.html
Contains extensive information on the Inca ice mummies.

Archaeology
http://www.archaeology.org/
Archaeology is an online and print publication of the Archaeological Institute of America. The site includes articles about current archeological topics and a news brief about the Iceman's return to Italy.

The "This is Rotten" activity aligns with the following National Science Education Standards:

Grades 5-8

	Science Standard C: Life Science

Populations and ecosystems: The number of organisms an ecosystem can support depends on the resources available and abiotic factors, such as quantity of light and water, range of temperatures and soil composition. Given adequate biotic and abiotic resources and no disease or predators, populations (including humans) increase at rapid rates. Lack of resources and other factors, such as predation and climate, limit the growth of populations in specific niches in the ecosystem.

Grades 9-12

	Science Standard C: Life Science

Matter, energy and organization in living systems:The distribution and abundance of organisms and populations in ecosystems are limited by the availability of matter and energy and the ability of the ecosystem to recycle materials.