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Origins: How Life Began

Viewing Ideas  Print this Teacher's Guide (PDF, 8 pages)

Origins: Earth is Born Viewing Ideas
Origins: Where are the Aliens? Viewing Ideas
Origins: Back to the Beginning Viewing Ideas

Before Watching

1. Have the class create a time line of major events using the program's 24-hour clock analogy. Draw two 12-hour clocks on chart paper. Ask students to imagine Earth's 4.6 billion-year history condensed into one day. Have students mark when think they the following occurred: formation of Earth's magnetic shield, creation of the moon, beginning of single-and multicelled life, and appearance of fish, insects, reptiles, dinosaurs, primates, and humans. Before they watch, assign students into groups to take notes on one or more of the above events.

2. Define "extremophile" (an organism that thrives under extreme conditions). Have students propose some environments on Earth where they think these creatures might live (in deep ocean environments near sulfur plumes, in Antarctic ice, in acidic hot springs). Discuss some advantages of being an organism in a harsh environment. (Extremophiles benefit by not needing to compete with other organisms for water, nutrients, and energy.)

After Watching

1. Have students revisit their predictions about what occurred when and mark the correct places on the time line. How much did students' original estimates differ from when events actually happened? What parts of the time line are most surprising to students? Why?

2. Ask students to recall the scientists in the program (to help with recollections, find the program transcript at www.pbs.org/wgbh/nova/ transcripts/3111_origins.html ). Have students name the different specialties involved in studying how life began (geologist, biologist, chemist). What kind of evidence did each type of scientist find?