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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 vs. climate variability and patterns
About Teaching Principle 4
Other materials addressing 4c
Observations are the foundation for understanding the climate system
About Teaching Principle 5
Other materials addressing 5b

Excellence in Environmental Education Guidelines

1. Questioning, Analysis and Interpretation Skills:C) Collecting information
Other materials addressing:
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.
Explore the map of concepts related to this benchmark
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.
Explore the map of concepts related to this benchmark

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

Disciplinary Core Ideas

MS-LS2.A3: Growth of organisms and population increases are limited by access to resources.

Science and Engineering Practices

MS-P3.2: Conduct an investigation and/or evaluate and/or revise the experimental design to produce data to serve as the basis for evidence that meet the goals of the investigation

MS-P4.4: Analyze and interpret data to provide evidence for phenomena.

MS-P5.2: Use mathematical representations to describe and/or support scientific conclusions and design solutions

MS-P6.1: Construct an explanation that includes qualitative or quantitative relationships between variables that predict(s) and/or describe(s) phenomena.

MS-P1.1: Ask questions that arise from careful observation of phenomena, models, or unexpected results, to clarify and/or seek additional information.

MS-P1.6: Ask questions that can be investigated within the scope of the classroom, outdoor environment, and museums and other public facilities with available resources and, when appropriate, frame a hypothesis based on observations and scientific principles.

HS-P1.1: ask questions that arise from careful observation of phenomena, or unexpected results, to clarify and/or seek additional information.

HS-P1.6: Ask questions that can be investigated within the scope of the school laboratory, research facilities, or field (e.g., outdoor environment) with available resources and, when appropriate, frame a hypothesis based on a model or theory.

HS-P3.5: Make directional hypotheses that specify what happens to a dependent variable when an independent variable is manipulated.

HS-P4.1: Analyze data using tools, technologies, and/or models (e.g., computational, mathematical) in order to make valid and reliable scientific claims or determine an optimal design solution.

HS-P5.3: Apply techniques of algebra and functions to represent and solve scientific and engineering problems.

HS-P6.1: Make a quantitative and/or qualitative claim regarding the relationship between dependent and independent variables.

Cross-Cutting Concepts

MS-C7.1: Explanations of stability and change in natural or designed systems can be constructed by examining the changes over time and forces at different scales, including the atomic scale.

MS-C1.2: Patterns in rates of change and other numerical relationships can provide information about natural and human designed systems

MS-C2.3: Phenomena may have more than one cause, and some cause and effect relationships in systems can only be described using probability.

MS-C3.3: Proportional relationships (e.g., speed as the ratio of distance traveled to time taken) among different types of quantities provide information about the magnitude of properties and processes.

HS-C1.1: Different patterns may be observed at each of the scales at which a system is studied and can provide evidence for causality in explanations of phenomena

HS-C2.2: Cause and effect relationships can be suggested and predicted for complex natural and human designed systems by examining what is known about smaller scale mechanisms within the system.

HS-C3.5: Algebraic thinking is used to examine scientific data and predict the effect of a change in one variable on another (e.g., linear growth vs. exponential growth).

HS-C6.1: Investigating or designing new systems or structures requires a detailed examination of the properties of different materials, the structures of different components, and connections of components to reveal its function and/or solve a problem.

HS-C7.2: Change and rates of change can be quantified and modeled over very short or very long periods of time. Some system changes are irreversible.


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