Description:
Dendrochronology or tree-ring dating is the scientific method of dating based on the analysis of patterns of tree rings, also known as growth rings. It can be used to determine certain aspects of past ecologies, particularly climate. This lesson is an introduction to dendrochronology. It begins with a short PowerPoint on dendrochronology. Embedded in the powerpoint is a link to a video defining and describing dendrochronology (“Danign with Tree Ringa”), and, a simple student interactive activity that allows them to learn how tree cores can be used to give information about past climate (“Build a Tree”). The lesson includes with three student activities
1. Tree Ring Detective
2. Dendrochronology and Climate Change Lab
3. Trees: Recorders of Climate Change (The Little Ice Age)
Standards Alignment:
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21st Century Skills: (learn more)
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Tools & Materials:
• data projector and computer
• tree cookie (if you have one – it’s a cross section cut from a tree – if not, diagram will work) and/or a real tree core
• Dendrochronology and Climate Change Lab activity: handout of tree cores worksheet (can be cut quickly using a paper cutter if you want to save some class time!)
• Trees: Recorders of Climate Change (The Little Ice Age) – tree cores copied along with data table (or entire handout)
o again, tree cores can be cut out ahead of time
o OR pre-made tree cores with wood doweling (see Teacher Notes above)
Time Required:
one to two 75 minute class periods
Process:
1. This lesson is an introduction to dendrochronology. It begins with a short PowerPoint on dendrochronology. Embedded in the powerpoint is a link to a video defining and describing dendrochronology (“Danign with Tree Ringa”), and, a simple student interactive activity that allows them to learn how tree cores can be used to give information about past climate (“Build a Tree”).
2. After the powerpoint, introduce and conduct the three student activities — see Attachments to this lesson. Teaching instructions can be found in each activity. These activities build on each other and are best done in the order listed below.
• Tree Ring Detective
• Dendrochronology and Climate Change Lab
• Trees: Recorders of Climate Change (The Little Ice Age)
Teacher Notes:
1. The “Tree Ring Detective” activity helps students understand how tree rings are formed and how tree rings can tell us about climate long before weather records were kept. The powerpoint is alos a good overview of this. Another source of information on this can be found at the NOVA site http://www.pbs.org/wgbh/nova/vikings/treering.html.
2. For the Dendrochronology and Climate Change Lab, circulate around the student groups to make sure that students are lining up their tree cores by matching up the tree rings.
3. While not necessary, the Trees: Recorders of Climate Change (The Little Ice Age) Activity is very powerful if simulated tree cores are used. To make a class set of tree cores for this activity,
a. purchase 5-9 pieces of the smallest diameter(red or green) wood doweling from a hardware store. (Each complete set of cores requires slightly more than 1 doweling.)
b. Using a hacksaw or a pair of secateurs (garden “scissors”) to cut the doweling to the correct lengths.
c. Glue the corresponding paper tree core to the piece of doweling.
d. Remember to record what year the doweling represents either by cutting out and gluing on the paper dates from the handout OR identifying each core with a letter and writing this in marker on the end of the core (the latter is much easier).
e. After all of this, prevent the paper on the outside from smudging by spraying the cores with a can of cheap hairspray or a can of fixative that you can purchase at an art or craft store. Both work well.
Do this in a well-ventilated area/outside.
Attachments:
• Dendrochronology Powerpoint
• Tree Ring Detective
• Dendrochronology and Climate Change Lab
• Trees: Recorders of Climate Change (The Little Ice Age)
• Tree Cores Worksheet
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