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Tree’s Life, A (FBCEC)

TopicBotany - Trees (Native)
Laboratory and Hands-on Activities - General
Summary
Participants will use tree cookies to learn about the tree it came from. They will read an excerpt from “A Sand County Almanac” by Aldo Leopold and use the literature to create their own histories for the tree cookies they are studying.
Grade Level5 - 12
Recommended SettingIndoor or outdoor classroom
LocationFred Berry Conservation Education Center, Yellville, AR
Contact
Education Program Coordinator, 870-449-3484
Duration45 minutes - 1 hour
Suggested Number of ParticipantsUp to 24
Objectives
  • Determine the age of a tree from its annual rings.
  • Use the tree cookie to read the tree’s history, to infer events in the tree’s life and when they happened.
Key Terms*

Annual rings

Cambium

Core sample

Dendrochronology

Heartwood

Outer bark

Phloem

Sapwood

Tree cookies

Xylem

Materials
  • “A Sand County Almanac” by Aldo Leopold
  • Copy sheet: Tree Cookie Investigation
  • Definitions for the following terms, each on a separate slip of paper: outer bark, phloem, cambium, xylem, sapwood, heartwood
  • Enough tree cookies for each participant (or pair of participants)
  • Hand lenses
  • Paper plates
  • Poster or transparency showing the parts of a tree trunk in cross section
  • Rulers
  • Tree cookie puzzles (for very young participants)
Background

Each year a tree produces an annual growth ring consisting of that year’s layers of xylem and phloem. Dendrochronology is the science of studying a tree’s rings to learn about past events such as a fire as well as environmental conditions that affect growth rate. Wider rings indicate rapid growth while narrow ones indicate slow growth. Tree cookies are cross-sectional slices of a tree’s trunk and can easily be used in the classroom.

Procedure
  1. Begin by reading excerpts from “The Good Oak” from Aldo Leopold’s “A Sand County Almanac.” Let the participants discuss what the excerpt means.
  2. Pass out the six definitions and display the poster (or transparency) showing the parts of a tree trunk. Have a participant read aloud a definition as you point out that area on the drawing. Provide any additional information to clarify the lesson. Discuss each tree trunk part in this way. Be sure to explain what annual rings are and how to recognize one.
  3. Give each participant (or pair of participants) a tree cookie. Ask them to find the parts of a tree trunk in their cookie. Explain what a tree cookie is and that a person can “read” the annual rings to learn about the tree’s life such as when there were droughts, fires, breaking limbs or lightning strikes. Explain that foresters can take a core sample to read this “history in wood” without cutting the tree. If available, show a core sample. Have participants use their cookie to answer the questions on Tree Cookie Investigation (copy sheet provided).
  4. Give participants a 24-inch strip of paper (adding machine paper will work) and instruct them to make a timeline representing their tree. They should label years in which events took place in the tree’s life (fire, drought, good year, etc.) Then, on the same paper, have them label years that represent special events in their own lives (started school, learned to ride a bike). Have them share their timelines with each other.
Modifications
  • For older participants (grades 3 - 12): Read a short story describing the life of a tree (see Project Learning Tree, activity 76, “Story about a Tree”) and have participants take notes. Have them draw a tree cookie on paper or a paper plate that would represent the tree in the story.
  • For younger participants (grades K - 2): Younger children can study tree cookies and count the rings to age them. Some can determine different events in the tree’s life. Give participants paper plates and let them create their own “cookie” according to their own ages and important things that occurred in their lives. For example, an 8-year old would make a cookie with eight rings. One ring might be close to another, indicating a year of difficulty with the loss of a pet. Another part could have rings that are far apart, indicating a good year, like the year he or she went on a fun trip or made a new friend. Let them be creative.
  • Provide participants with tree cookie puzzles. Once the puzzles are assembled, explain how one ring forms each year and that age can be determined by counting its rings. If rings are close together, the tree didn’t grow much that year. The tree grew a lot in years where the rings are far apart. Participants can point out those years on their puzzles. Finally, let the participants examine some actual tree cookies.
Review
  • Describe factors that might cause a particularly thin annual ring.
  • Explain how a dendrochronologist might obtain climate data in northwest Arkansas in the 1920s and 1930s.
  • Name and describe six main parts of a tree’s trunk.
Resources
Related Documents
Glossary

Annual rings – rings visible on the wood of a cut tree

Cambium – a thin layer between the xylem and phloem of plants

Core sample (dendrology) – the inner sample of the heartwood and sapwood extracted by using an increment borer

Dendrochronology – method of scientific dating based on tree-ring growth patterns

Heartwood
– older, inactive central wood of a tree or woody plant which is usually darker and denser than the surrounding sapwood

Outer bark – the external, mostly dead tissue that forms a protective barrier between plant stems, branches and roots and the abiotic and biotic environment; distinct and separable from the wood itself

Phloem – the living tissue in vascular plants that carries nutrients, particularly sucrose, to all parts of the plant

Sapwood – the outer portion of wood that lies between the cambium and heartwood

Tree cookies – a cross section sample of a tree

Xylem – complex tissue found in vascular plants