Tuesday, April 20, 2010

My Use of Timelines in the Classroom

For much of my life, I have been fascinated by human prehistory. I don’t know when this started. It may have been a result of my reading Jacob Bronowski’s The Ascent of Man, a pun on Darwin’s famous Descent of Man. I read that book in high school, which traced humanity’s development of knowledge through science and was based on a 13-part BBC series which I never saw. I did very little reading of any kind in high school, but I remember that my father gave me that book and I couldn’t put it down. It was fascinating. During college a few years later, I took a course in human evolution and at one point while reading about the evolution of the remarkable human hand, I stopped what I was doing and stared in wonder at my own hand. I graduated from college with a topical bachelor’s degree in “Prehistoric Studies,” something which embarrassed me and which I therefore conveniently changed to “Cultural Anthropology” when anybody asked about my college major. Once while living in Peru, I stayed up late with a couple of friends who shared the pension with me in downtown Lima. As the evening wore on, I eventually launched into a very animated lecture about human prehistory, physically acting out all the stages of human evolution from Ramapithecus to the present. It may have been my very first successful lecture on the subject. My small audience talked about that incident for weeks. (Here's a short, 4-minute lecture on human prehistory using a timeline analogy:

When I taught 5th grade in 2003, I had to delve a little into prehistory to introduce my class to the early Native Americans of California. We made a timeline beginning with the earliest human settlement in our local community of Topanga Canyon, something we discovered while reading about an archaeological spot called the ‘Tank Site.’ The dig took place in the late 1940s, and was situated only a few miles from our school. We read about it in a chapter from our local historical society’s book, The Topanga Story. The Tank Site was first inhabited by native peoples over 7,000 years earlier. I wanted our class timeline to begin with those first known inhabitants of Topanga, continue up through the earliest Europeans to homestead in the area (the Santa Maria family), and end with the present era. I determined that I would need enough space on the timeline to plot important historic events such as the Revolutionary and Civil wars, as well as Westward Expansion, since these were also required subjects for 5th-grade social studies. I figured that 10 feet of timeline would suffice to chart these latter historical events. However, I wanted the timeline to be accurately ‘to scale,’ meaning it didn’t compress time at any point like so many timelines found in textbooks. As a math assignment, I had students calculate the total length of the timeline from the present back to the Tank Site, with at least 10 feet reserved for the most recent 200 years of our history. This meant that each foot had to represent 20 years of history, which is roughly one human generation. Several days were devoted to planning this timeline, determining its length, assembling materials (stacks and stacks of old homework were creatively glued together by teams of students), and figuring out how to hang this long timeline from the walls our room. In the end, the timeline was over 350 feet long, and spiraled a couple of times around the high walls in our large brick classroom. It was a dramatic sight, and impressive to see how the native peoples had inhabited the timeline for over 340 feet, while Europeans only begun homesteading within the last 7 feet of the timeline. The timeline created quite an impression about the longevity of the native population when compared to the recent European settlers. Sometimes we would play the ‘foot’ game, where we would randomly mark a short foot-long section of the timeline at any point along its 350-foot length. We would then make up a story about a group of native peoples who lived during that 20 year period, what adventures they had, what animals they hunted and plants they gathered, who grew up into what kind of person, what stories were told, what difficulties were encountered, and what dreams and visions were held. This helped us to give life to the timeline and the people who lived for so many generations before European contact.

The following year, when I taught 6th grade, timeline activities became more dramatic. Social Studies for 6th grade requires more than just a look at Native Americans, but involves the study of human prehistory back through our split from the apes. Suddenly a 7,000 year timeline was replaced with a 3.7 million year-long timeline. This ancient date marked the moment when two bipedal (fully upright) early hominids (human ancestors) left very human-looking footprints in some fresh volcanic ash in what is now Laetoli, Tanzania, Africa. Because those Australopithecine footprints were so well-preserved and carefully photographed when they were discovered in 1976, I knew that such an event would make a dramatic visual beginning for our human evolution timeline in 6th grade. On this timeline, I planned to have students plot the first stone tools (about 2.5 millions years ago), the discovery of fire (700,000 years ago), the emergence of modern humans (200,000 years ago), the earliest cave paintings (about 40,000 years ago), the first farming communities and civilizations (beginning about 11,000 years ago), the discovery of coal power (the Industrial Revolution), and up to the present day. As 6th-grade prehistory covered a much greater period of time, with a total span of years much longer than it had been in 5th grade, the students’ ability to conceptualize these numbers and to construct an accurate timeline, represented an immense challenge.

In much of my work with 6th graders, conceptualizing numbers of great size has always been extremely difficult. Whether we are making timelines of human history, studying the distance to ‘nearby’ stars, or discussing the numbers of casualties from disasters like the South-Asian tsunami, large numbers are simply too hard to fathom. Yet in spite of the difficulty, I have discovered that challenging ourselves to make these leaps of mind, to represent these models of size and distance, is intellectually enabling, cognitively captivating, and emotionally stimulating. If we were to take the previous year’s 350-foot timeline -which stretched almost three times around my room winding for 7,000 years down to the prehistoric Tank Site natives- and continued that timeline back to the fossilized African footprints of early ancient humans, the timeline would obviously be much, much longer. But just how long? This is where numbers become hard to grasp. Keeping the timeline to scale, it would now stretch over 185,000 feet in length, continuing on for 35 miles! This means that a timeline of human history -in which the last 200 years compressed to 10 feet of timeline- would have to be 35 miles long in order to trace our history back to our earliest upright ancestors, 24 miles long to go back to the first stone tool makers, and 7 miles long to take us back to the controlled use of fire by Homo erectus. It was clearly impossible to make a 35-mile timeline, but the message was clear; human beings and their most recent upright ancestors, inhabited the earth for far longer than most of us had ever been able to appreciate. As a class, we ended up making a more compressed timeline in our room that stretched just 120 feet around the room, and upon which all of human history back to Africa’s “Lucy” (Australopithecus) was contained. On such a timeline, each foot of distance now represented 30,000 years of history. On this timeline, the emergence of farming, human settlements, and all of human civilization was contained within the last four inches. On this timeline, the industrial revolution occurred within the last one-tenth of an inch. A new and dramatic message emerged from this timeline; During 120 feet of the timeline, human ancestors lived in nomadic, hunting-and-gathering groups, but such a tribal, foraging lifestyle was abandoned during only the last few inches of human history. Industrialization and environmental destruction had only begun within the last fraction of an inch. Such a timeline revealed some compelling truths about our species, illustrating how recently we have dramatically changed have the way we relate to the earth, to nature, and to each other.

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