If you ever have trouble getting middle level students interested in geologic time, try combining it with metric measurement! I use this activity to practice the use of metric measurement, sequencing, and some facts associated with the study of earth’s history.

Materials: measuring tape or meter sticks, string or yarn, 19 large index cards, tape, 30 dowel rods for holding the time line and for the data, typed earth history data

Procedure:
1. From the data listed below, type each of the facts, the time period, and the scaled-down metric measurements that would correlate to a time line. You might consider, having students calculate the metric measurements for the cards. Use large print and tape them to large index cards.

2. Attach the index cards to thin dowel rods so that the students can use them as stakes.

3. While outside and with student help, measure the distance of 46 meters in colored yarn and stake it about 50 cm off the ground. This gives a guide for placement of the stakes. The 46 meters represents the 4.6 billion years of Earth’s age.

4. Hand out the cards attached to the stakes. These should be in random order. Students must decide where to position themselves along the "time line" in the schoolyard.

5. Once in position, each student reads aloud his or her event that is associated with that time period.

Discussion Topics:
1. How does it feel walking through Earth’s history?

2. Do you think about certain events differently after walking through the time line?

3. What do you notice about the spacing of events?

4. Why are there such big gaps in some places in the line and smaller ones in other places?

5. Why do you think it took so long for evidence of life to appear on Earth?

Earth History Data:

4.6 billion (46m) Earth formed.
3.9 billion (39m) Oldest rocks found today formed in southwest Greenland.
3.5 billion (35m) Life on Earth begins.
3.0 billion (30m) First fossils form: algae, fungi, and bacteria are abundant.
600 million (6m) Jellyfish, sponges, and worms are abundant.
480 million (4.8m) First primitive fish appear.
400 million (4m) Earliest land plants are ferns and mosses.
360 million (3.6m) First insects appear.
350 million (3.5m) First land animals are amphibians.
300 million (3m) Much of continental land masses are underwater.
200 million (2m) First dinosaurs appear.
180 million (1.8m) Huge, single land mass called Pangaea begins to break into continents.
136 million (1.36m) First flowering plants appear.
  65 million (65 cm) Dinosaurs extinct and North American Rockies begin to form.
      300,000 (3mm) Oldest known remains of modern human beings, Homo Sapiens, come from this time.
        10,000 (.10mm) Most recent Ice Age ends. Farming revolution begins.
          6,000 (.06mm) Recorded history begins in ancient Egypt.
          2,000 (.02mm) Beginning of modern calendar.
             100 (.001 mm) Industrial Revolution begins; humans begin to drastically change the environment.