Introduction: What is Temporal Thinking?
This summary was written by Carol Ormand, SERC.
Cognitive Understanding of Time and Events
Humans think of time as a series of events (Shipley and Zacks, 2008, cited in Resnick, 2012). One cognitive theory about how we remember events is that we store a combination of numerical and contextual information (Huttenlocher, et al., 1988, cited in Resnick, 2012). For example, we remember the dates of some events (birthdays, anniversaries), but we recall other events in terms of what else was happening at around the same time ("that was during my second year of college" or "that was the year after our basement flooded"). This works well when we have a densely populated mental timeline, so that as we learn about events we can place them in a historical context, accurately. However, it does not work particularly well when we have a sparsely populated mental timeline. With a weak framework of events, the accuracy of our memories of when events occurred is compromised Resnick, 2012). One implication of this for educators is that it is important for students to learn a set of key events, for whatever time frame we want them to understand, and it's best if those key events are distributed relatively evenly throughout the time span.
Understanding Deep Time: Challenges and Strategies
Given how humans conceptualize time, it is not surprising that we often use timelines to teach about time, in disciplines as disparate as history, archeology, and geology. However, as we contemplate longer and longer spans of time, a linear representation becomes inadequate. As one paleontologist notes, "the corollary to 'Time is Long' is 'Space is Large' " (Daley, 2012). If we scale the approximately 4.5 billion years of Earth's history to a comprehensible length, time is so compressed that the smallest distances we can easily measure still represent an incomprehensibly long span of time. For example, if 4.5 billion years is scaled to a 45 meter long timeline, 1 centimeter represents one million years, and 1 millimeter represents 100,000 years. "Changing the scale (e.g., 1 inch = 1 year) simply shifts the problem, as 4.5 billion inches is equally incomprehensible, even when converted to 71,022 miles, or 2.8 times the circumference of the Earth" (Daley, 2012). The problem becomes even more extreme when we consider the approximately 15 billion year history of the Universe.
One particularly clever solution to this scaling problem is the Trail of Time along the south rim of the Grand Canyon. Although most of the Trail of Time uses a linear scale, the recent end of the Trail utilizes a logarithmic approach to help visitors understand the linear scale, moving from 1 meter = 1 year through 1 meter = 10 years to longer and longer time scales, until 1 meter = 1 million years. This telescoping of recent Earth history makes the time scale far more accessible (Semken et al., 2009, cited in Semken, 2012).
It's also fairly common to use analogies to help students understand Deep Time. However, many common analogies for Deep Time present cognitive challenges of their own, or have the potential to create misconceptions. Fortunately, there are practical guidelines that educators can use to use analogies effectively, as explained in Using Analogies to Teach about Time. Other strategies for scaffolding student understanding of Deep Time include starting with understanding large numbers, as Roger Steinberg does, or using astronomical distances, as Erika Grundstrom explains.
Summary
Students struggle with time scales and intervals that are beyond their personal experiences, with the complex interactions of slow processes over long time scales, and with the enormous numbers involved in Deep Time. A sophisticated understanding of these temporal concepts is an essential foundation for unraveling the complex histories of civilizations; of species; and of the Earth, our solar system, and the Universe. It is also key for contextualizing the natural and anthropogenic changes occurring on our planet today.