Theme: Honing Math
Skills in the Garden
Measuring
Tree Growth: Two Tree Inquiry Challenges
Puzzling Out Tree Growth
Challenge your students to figure out just where tree growth
takes place. (Trees add length from the tips of twigs and rootlets,
and width when the cambium adds new xylem and phloem cells.)
They might mark different spots on twigs, then measure the distances
between markers over time. If they observe twigs from the tips
down, they'll notice fine lines encircling the twig where the
bark color changes. These mark the position of the last terminal
bud -- the end of last year's growth. (On conifers, a shift
in needle color typically signifies new growth.) Students could
also explore whether twigs on different trees grow at the same
rate, or what conditions (temperatures, pests, diseases, water)
seem to affect the amount of annual growth.
Students might suggest measuring the circumference of the trunk
or branches. (This type of growth may be difficult to quantify
in a short period!) If you have access to tree slices or "cookies,"
students can count and examine annual growth rings formed as
the cambium adds new cells. They might even try to compare weather
records with the appearance of unusually large or small rings.
You can also use these slices to examine the inner workings
of the trunk.
Measuring Up
How high is up? Challenge students to figure out how to measure
the height of a tree, then test their theories. Here is one
sunny-day option. Drive a stick straight into the ground in
a sunny spot. Measure the length of stick from the ground to
the top. Then measure the length of the stick's shadow and the
length of the tree's shadow. The tree height equals the length
of its shadow multiplied by the stick height divided by the
stick's shadow (shadow of tree/ height of tree = shadow of stick/
height of stick).
Author: Eve Pranis
Next Page
Page 1 2
3 4
5 6 7
8
-lo.jpg)
