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Dendrochronology - Trees: Recorders of Climate Change
http://eo.ucar.edu/educators/ClimateDiscovery/LIA_lesson5_9.28.05.pdf

NCAR - National Center for Atmospheric Research

In this activity, students are introduced to tree rings by examining a cross section of a tree, also known as a 'tree cookie.' They discover how tree age can be determined by studying the rings and how ring thickness can be used to deduce times of optimal growing conditions. Next, they investigate simulated tree rings applying the scientific method to explore how climatic conditions varied over time.

Activity takes about 50-60 minutes.

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Topics

Proxy Data
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Grade Level

Middle (6-8)
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High School (9-12)
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Although activity is written for high school it can easily be used in middle school.

Climate Literacy
About Teaching Climate Literacy

Climate change is a significant and persistent change in an area’s average climate conditions or their extremes. Seasonal variations and multi-year cycles (for example, the El Niño Southern Oscillation) that produce warm, cool, wet, or dry periods across different regions are a natural part of climate variability. They do not represent climate change.
About Teaching Principle 4
Other materials addressing 4c
Environmental observations are the foundation for understanding the climate system. From the bottom of the ocean to the surface of the Sun, instruments on weather stations, buoys, satellites, and other platforms collect climate data. To learn about past climates, scientists use natural records, such as tree rings, ice cores, and sedimentary layers. Historical observations, such as native knowledge and personal journals, also document past climate change.
About Teaching Principle 5
Other materials addressing 5b

Excellence in Environmental Education Guidelines

1. Questioning, Analysis and Interpretation Skills:C) Collecting information
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C) Collecting information.
2. Knowledge of Environmental Processes and Systems:2.1 The Earth as a Physical System:A) Processes that shape the Earth
Other materials addressing:
A) Processes that shape the Earth.

Benchmarks for Science Literacy
Learn more about the Benchmarks

Scientific investigations usually involve the collection of relevant data, the use of logical reasoning, and the application of imagination in devising hypotheses and explanations to make sense of the collected data.
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The earth's climates have changed in the past, are currently changing, and are expected to change in the future, primarily due to changes in the amount of light reaching places on the earth and the composition of the atmosphere. The burning of fossil fuels in the last century has increased the amount of greenhouse gases in the atmosphere, which has contributed to Earth's warming.
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Notes From Our Reviewers The CLEAN collection is hand-picked and rigorously reviewed for scientific accuracy and classroom effectiveness. Read what our review team had to say about this resource below or learn more about how CLEAN reviews teaching materials
Teaching Tips | Science | Pedagogy | Technical Details

Teaching Tips

  • Educators should explain to students how the matching of tree rings between trees of different ages is done (by searching for patterns to extend the record past the life of just one tree).
  • Great opportunity to touch on radiometric dating techniques that allow scientists to absolutely date trees that are found in bogs and other environments.
  • Trees don't die from coring - students will probably ask.
  • Educators should explain to students the elliptic growth of trees.
  • Educators should indicate that dendrochronology is a complex science and large uncertainties can exist.
  • Educators might want to provide alternatives to a simple cross section of tree rings and provide a better explanation of tree coring.
  • Educators may want to project images instead of using overhead transparencies.
  • Additional Resources links on page 4 don't work. Two of them are incorrect and one of the NASA websites is not available anymore.
  • For a good alternative activity on dendrochronology see Signs of Change: Studying Tree Rings activity at http://www.climatechangenorth.ca/section-LP/LP_28_HI_M_nancy.html.
  • Additional resources and science articles about dendrochronology at the Arizona Tree Ring site http://www.ltrr.arizona.edu.

About the Science

  • The links between tree ring thickness to past climate and other influences on tree ring thickness are not well described and should be provided through supplemented materials by educator.
  • Lots of background materials for students to understand the scientific process.
  • Comment from scientist: Sometimes wood from ancient structures, when aligned with chronologies from living trees, extends a chronology even further back than indicated in activity. The date of the structure provides an approximate date of when the trees were felled. One chronology for river oaks from southern Germany extends more than 10,000 years, and another for bristlecone pine in the White Mountains, California extends more than 8,500 years.
  • More background information: Esper, J., Cook, E.R., and Schweingruber, F.H. (2002). Low-frequency signals in long tree-ring chronologies for reconstructing past temperature variability. Science, 295, 2250-2253.

About the Pedagogy

  • Good example of how to use analysis of data and graphs to infuse content knowledge.
  • Plotting graphs and analyzing data addresses needs of visual learners.
  • Activity does excellent job of supplying good questions for educators to ask students at the beginning of lesson and to scaffold learning.

Technical Details/Ease of Use

  • Well designed and organized.
  • All materials are available in printable form.

Related URLs These related sites were noted by our reviewers but have not been reviewed by CLEAN


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