Trees Tell a Story

Elizabeth Barrett-Alexander

Columbus Elementary School

Summer Research Program for Science Teachers                                     

August 2012        

Subject: Elementary Biology and Environmental Science

Grade Level: 3-5

Time Requirement: Three science periods (2 ½ hours+)

Topics Covered in this Lesson: how organisms (trees) obtain resources for survival, counting and dating tree-rings, plant/tree structures and function

Learning Objectives (SWAT):

·        Identify parts and functions of a tree

       1.     Bark – protection

       2.     Rings- growth of cambium

       3.     Pith – center of tree

       4.     Xylem and Phloem – transfer of water, nutrients etc…

·        Recognize and count annual growth rings to date tree

·        Identify ring patterns (width differences) or markings

·        Use the ring patterns to tell a story about the growing conditions when the tree was alive

Vocabulary:  annual growth ring, precipitation, drought, temperature, cambium, xylem, phloem

Materials:  tree ring samples (cores or cross section), hand lens, toothpicks, and science notebooks

Procedure: 

1.  Review how trees obtain needed resources in order to survive: air (C0₂/O₂), water, minerals, sunlight etc…  Talk about an average tree’s life cycle and life span. 

2.  Review and discuss parts of a tree: structures and function.

3.  Hand out tree core/cross section samples. (Photocopies of scanned cores or cookies could be substituted.)  Have students make observations and discuss with team members what they see.

4.  Whole class discussion and diagramming of observations.  Students diagram in notebooks.  Add new vocabulary: pith, rings, bark. 

5.  Hand out hand lenses for students to make more careful observations and begin to count rings.  (What are the rings?  Usually a few students know that the rings have something to do with the age of the tree)  Add new vocabulary: cambium, xylem, phloem.

6.  Students systematically count rings from bark to pith.  Discuss counting techniques and the importance of replication of data and using similar methods for counting.

7.  Students calculate the age of their tree sample (bark is considered present year for this activity).  Using current year as start date, students will subtract to find age of tree.

NEXT DAY…

 8.  Students observe tree sample looking for differences in rings widths and patterns.  Discuss what these differences could mean.  Students discuss with team members ideas for different rings widths, patterns or marks. 

9.  Discuss the idea that the tree can only add annual growth rings when its needs are met.  What are the trees needs?  Air, water, minerals and sunlight- light and temperature.

10.  Question: how could the trees needs account for rings sizes and patterns?  Allow students to make connections such as I need to eat to grow.  So if I didn’t have too much food, I might not grow very well.

11.  Using a sequence map, have the students tell the story of their tree’s life.  Be sure to include important events as shown in rings.  Student can decide what factors led to the tree growing well or having difficulty.

12.  Students share storylines. 

Assessment:

Give 1/ 2 the class climate information such as precipitation or temperature data.

 EXAMPLE:

With the other half getting a copy of a tree ring sample.  Students will need to match the ring samples to the climate data.  They will then defend their selection. 

Standards (NGSS-draft)

3. EIO Environmental Impacts on Organisms

c. Analyze data to describe how humans, like all other organisms (TREES), obtain living and non-living resources from their environment.

e. Use evidence to argue that some changes in an organism’s habitat can be beneficial or harmful to the organism.

4. PSE Processes that Shape the Earth

b. Obtain and communicate information about how patterns in tree rings and ice cores are used as evidence to describe the recent history of Earth’s climate.

5. ESI Earth Systems and Their Interactions

c. Construct models to describe systems interactions for the geosphere, hydrosphere, atmosphere, and biosphere and identify the limitations of the models.

h. Provide evidence to explain how increases in Earth’s temperature can affect humans and other organisms.