Monday, June 4, 2012

Students in Laramie Junior High’s Scientific Perspectives class learn about leaves interaction with light (or electromagnetic radiation)

Students in Ms. Julie Eakin’s eighth grade scientific perspectives class at Laramie Junior High learned how different leaves interact with light and how they appear to human eyes.

Fifteen students were introduced to the principles of electromagnetic radiation and then how a leaf’s interaction changes based on factors such as pigments (chlorophyll), water content, surface area, and stress (insect damage, for example).


Based on these concepts students developed a hypothesis for comparing the reflectance properties of each leaf.  With ALTA ™ Spectrometers, they measured the spectral reflectance in 10 different regions of the electromagnetic spectrum.  Using standard reflectance values measured from white and black surfaces, they calculated percent reflectance for each leaf and plotted them against wavelength.

Analyses of these plots, termed the spectral signatures, revealed marked differences in the way each leaf interacted in different regions of the spectrum.  For example, a freshly cut aspen leaf and a blade of grass harvested several hours earlier had markedly different reflectance properties (figure).  Comparing results from each team, students could see how a leaf’s pigments, surface area, and vigor influenced its reflectance properties. 

This outreach activity was conducted on May 8 (2012) by Ramesh Sivanpillai, WyomingView coordinator, as part of AmericaView’s Earth Observation Day activities aimed at introducing teachers and students to remote sensing science and applications.