Using Powers of 10 to Help Students Develop Temporal Benchmarksby: Mette Elisabeth Schwartz

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One of the greatest challenges for middle school Earth science teachers is helping our students get a feel for the magnitude of the long spans that make up Earth’s history. The intent of the strategy presented here is to help middle school students get a feel for the real sizes of powers of 10, and then help them use that understanding by connecting it to a period of time that means something to them, such as a year. The hope is that by connecting a period of time they understand with a power of 10 for which they have developed a benchmark; geologic time will be more meaningful to middle school students.

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Reviews (2)
  • on Tue Jul 29, 2014 6:19 PM

This well written article is a must read if you teach anything related to geologic timescale. The way that Ms. Schwartz reconciles the use of relative scales with the absolute magnitude of the numbers is easy to understand and classroom ready. The time benchmark chart is worth a look on its own, but it is just one of many resources here. Presented this way, students will be able to make connections to their own lives, and should be better able to deepen their understanding of the concepts because it has become relevant.

Caryn Meirs  (Smithtown, NY)
Caryn Meirs (Smithtown, NY)

  • on Tue Feb 07, 2012 6:02 PM

The very large numbers associated with geologic scales are difficult to comprehend even when using distance as an analogue for time. The author suggests associating powers of 10 with real-life examples to help make meaning of very large numbers. By creating time benchmarks, 6 through 8 graders came up with real life examples of how long, how often, or how many a power of ten might encompass. Here are some examples. How many heartbeats in a minute (in powers of 10)? How many breaths? How long is an NBA basketball game quarter? How long has it been since the end of the Civil War? After students create examples that span 100 million years, they are ready to learn about events in Earth’s geologic history. The author provides a sample time benchmark chart and explains the pedagogical thought behind this strategy. Teachers using the units of Ma (for millions of years) may find this technique helpful to use with students trying to grapple with very large numbers.

Carolyn M  (Buffalo Grove, IL)
Carolyn M (Buffalo Grove, IL)

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