On the Cutting Edge - Professional Development for Geoscience Faculty
Rates, Dates and Geologic Time: Teaching about the Temporal Aspects of Geoscience
Cutting Edge > Rates and Time > Teaching Activities > Hierarchical Alignment of Timelines

Hierarchical Alignment of Timelines

Ilyse Resnick
Psychology graduate student, Temple University
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This activity was selected for the On the Cutting Edge Exemplary Teaching Collection

Resources in this top level collection a) must have scored Exemplary or Very Good in all five review categories, and must also rate as “Exemplary” in at least three of the five categories. The five categories included in the peer review process are

  • Scientific Accuracy
  • Alignment of Learning Goals, Activities, and Assessments
  • Pedagogic Effectiveness
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This page first made public: Feb 22, 2012


In the hierarchical alignment activity students progressively and hierarchically align scale information to a spatial linear representation. The progressive alignment of scales may alleviate the conceptual dissimilarity between human scales and extreme scales by providing greater structural alignment across changes of scale. The hierarchical organization highlights how each temporal scale is related to the others, helping to populate each scale with boundary information by providing internal structure of magnitude relations within event boundaries.

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The hierarchical alignment activity has been used with undergraduate students in an introductory-level geoscience course for non-majors.

Skills and concepts that students must have mastered

Students will need to have a basic understanding of addition, subtraction, multiplication, and division. An understanding of proportional reasoning and/or the target scales of interest may be helpful; however they are not necessary. The aim of the hierarchical alignment activity is to foster a linear representation of scale information by moving from familiar scales to unfamiliar scales.

How the activity is situated in the course

The hierarchical alignment activity was conducted as a stand-alone exercise.


Content/concepts goals for this activity

The content/concept goals include understanding the magnitude information implicit in the content being presented. For example, in teaching the Geologic Time Scale, the hierarchical alignment activity serves to present the relative magnitudes of the divisions of the Geologic Time Scale and how that magnitude relates to human scales.

Higher order thinking skills goals for this activity

Higher order thinking skills goals include critical thinking about temporal content and proportional reasoning.

Other skills goals for this activity

Other skills goals include working in groups (this activity can be conducted in groups/pairs), and also practices the mathematical skills necessary in proportional reasoning.

Description of the activity/assignment

In the hierarchical alignment activity, students are given multiple opportunities to align time to space in a linear representation. They begin by scaling a familiar amount of time (e.g. a personal time line) to a spatial representation (e.g. a meter stick), and progressively align increasing/decreasing amounts until completing the target unfamiliar time line (e.g. geologic time). For example, in the hierarchical alignment of geologic time, students can work through 10 time lines: personal, human lifespan, American history, Recorded history, human evolution, Cenozoic, Phanerozoic, Proterozoic, Archean, and then Hadean.

While the amount of time varies, the amount of space remains constant: in this example, students align all new temporal scales to one meter. For each time line, students are asked to locate specific events, hierarchicaly organized divisions of time, and the length of the time line in order to engage the students in thinking about that temporal scale. Additionally, every time students align a new temporal scale to space, they locate all previous scales relative to the current scale.

Determining whether students have met the goals

Students were assessed on their understanding of the relative proportions of the Geologic Time Scale one month after completing the hierarchical alignment activity for geologic time as part of a laboratory exam. The assessment items came from the Geoscience Concept Inventory (Libarkin, et al., 2005) and a measure developed for use with middle school students (Barghaus & Porter, 2010). The Geoscience Concept Inventory has multiple items having to deal with temporal understanding and rates of change. We are currently developing more assessment items.

Barghaus, K. & Porter, A. C. (2010, April). Building aligned assessments for middle school science teachers and students. Paper presented at the annual meeting of the American Educational Research Association., Denver, CO.

Libarkin, J.C., Anderson, S.W., Dahl, J., Beilfuss, M., & Boone, W. (2005). Qualitative analysis of college students' ideas about the Earth: Interviews and open-ended questionnaires. Journal of Geoscience Education, 53(1)

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