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Rings as Keys to the Past

A Case of Dendroarchaeology


Gary L. Patterson
Department of Biology
Utah State University--Tooele


This flipped case study was written to provide foundational understanding of woody stem (tree) anatomy and to illustrate how scientific support is used to determine the age of objects made of wood, which in turn may affect an object's value. The narrative was inspired by a 2004 article by Henri Grissino-Mayer et al. that deals with questions concerning the authenticity of the so-called "Messiah" violin, a reputed Stradivarius, based on stylistic and historical grounds as well as conflicting sets of tree-ring dates. The case provides general biology, botany, and perhaps forestry instructors a chance to show relevancy for learning basic tree anatomy and the process of growth in plants that produce woody stems. Additionally, a primary focus of the case is to give students the chance to experience the preliminary steps of a process used by dendrochronologists to determine the age of wooden objects. The case was developed for general non-majors biology courses taught in high school, college/university, or for informal science education settings with adult learners.


  • Explain phenomena logically and specifically, using data or other evidence when necessary to support explanations.
  • Demonstrate a transfer of knowledge gained virtually to a "real" product.
  • Convert distinctive patterns on paper into "real" data, i.e., the age of a wood sample.
  • Understand the lateral growth process of plants that produces woody stems, i.e., trees.
  • Recognize the ability of tree ring growth patterns to "record" local, regional, and even global events.
  • Gain understanding as to the usefulness of trees' consistent growth pattern to identify when human-caused or natural events occurred, such as injury, fire, drought, insect infestations, floods, or logging.


Crossdating; dendroarchaeology; dendrochronology; tree rings; primary growth; secondary growth; Laboratory for Tree Ring Research; luthier; skeleton plotting; tree anatomy; core; wooden musical instruments; Stradivari; Stradivarius; violin; Grissino-Mayer

Topical Areas


Educational Level

High school, Undergraduate lower division, General public & informal education



Type / Methods

Flipped, Interrupted, Laboratory



Subject Headings

Botany / Plant Science  |   Biology (General)  |   Forestry  |  

Date Posted


Teaching Notes

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Supplemental Materials

The case includes the following appendices to be used with the skeleton-plotting activity described in Part IV of the case.

  Appendix 1
  Appendix 2
  Appendices 3 and 4
  Appendix 5

Answer Key

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The following video(s) are recommended for use in association with this case study.

  • How Old Is This Violin?
    This video serves as a hook into the case as “Professor P” shows a violin to various people and asks how they might determine its age. Running time: 3:24 min. Created by Gary Patterson, John Wild, and Scott Bailey for the National Center for Case Study Teaching in Science, 2016.
  • Why Do Trees Have Rings?
    In this video James May explains the difference between primary (height) and secondary (width) growth of trees, and the color difference between early and late wood. Running time: 3:37 min. Produced by Brit Lab, 2013.
  • Secondary Growth and the Formation of Annual Rings
    Students use a paper model to explain how the vascular cambium helps form annual rings in trees. Running time: 1:58 min. EuniceBiology, 2013.
  • SFRC Increment Borer
    Demonstration of coring a tree with an increment borer. Running time: 4:13 min. Produced by UF-IFAS School of Forest Resources and Conservation, 2013.


Adam W. Hrincevich
Biological Sciences Department
Louisiana State University
Baton Rouge, LA


A helpful alternative for the increment borer video is: "Dendrochronology: How to use an increment borer" at In this video, Dr. Bill Schuster explains why scientists age trees, what instrument is used to take tree cores, and the proper technique used to do so. Running time: 8:56 min. Black Rock Forest, 2020.

Also, I found the instructions for the skeleton plotting exercise (Part IV of the case study) very challenging. It took me a good hour and many attempts to decipher how to accomplish this task. The video link from PBS ( was probably the best guidance on how to interpret the paper core samples and growth ring data.

I am not sure if you are looking for suggestions for this exercise, so I am going to apologize in advance for my contributions below. Overall, I think this is a very interesting "hands on" exercise that I am trying to incorporate into my online BIOL lab this semester.

  1. Appendix 3: The strip immediately below the instructions (1655-1740) is extra and should not be included since it is confusing as to where it would be used.
  2. Perhaps a video/screen capture of someone doing a skeleton plot from a hypothetical sample core would REALLY help tie together the approach of this technique. For example, using the website to perform a video demo would be super helpful for many students. That is what I did for my students because I know that many of them would give up out of frustration or the inability to really follow the directions for this technique.
  3. For Part V, the interpretation of the graph (especially the red circled region) needs to be explained in more detail. I was unsure how the conclusion was made that "Henri and his colleagues used these data to determine that the spruce wood in the top of James' violin came from a tree that had been cut down in 1686!" based on what was presented in the graph.
  4. For Part V, how are students able to answer Question 3 without some background information or being provided with the information from the website
  5. The answer to dating the paper core should be addressed more directly. If students did the skeleton plotting correctly, they would match that core sample up with the years ~1628-1740 on the master chronology strips, correct? I think this answer needs to be more obvious since that was the whole purpose of the activity in Part IV (which took the most time).