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The Challenge:

To determine the rate of transpiration in the transpiration lab in the Advanced Placement lab book (Investigation 11) requires that students measure the surface area of the leaves they are using. In the “old days”, students traced leaves on graph paper or used a mass method. I wanted to discover a quicker and more accurate way to calculate surface area.  I came across a great program called ImageJ that not only does a great job determining surface area of leaves from a phototgraph, it also is a tool with enormous capabilities related to quantifying a variety of aspects of digital images.

A Solution:

My search to find a way for my students to determine leaf surface area led me to a great tool called ImageJ. ImageJ is a free image processing program developed by the National Institute of Health and the Laboratory for Optical and Computational Instrumentation (University of Wisconsin). Basically, any video or photo taken can be analyzed. My students have used it to count the cells from pictures they took under the microscope, as well as measure the length of the epicotyl and hypocotyl of a germinating seed. One of my students even used ImageJ to track and measure the movement of marine hermit crabs in an experiment they designed. There are hundreds of applications. Additionally, there is not one way to use the program. I would suggest having your students look for YouTube videos or online instructions for their specific goal.

Leave a comment if you have any questions.

Resources:

https://fiji.sc/ - This is the best ImageJ processing package

https://www.youtube.com/watch?v=BwJRFkQh5XE – This is a YouTube video with instruction to install FIJI (PC)

https://kb.franklin.uga.edu/display/public/FOKFC/Fiji+%28ImageJ%29+Installation+Instructions - instruction to install FIJI (Mac)

Below are specific instructions for measuring the surface area of a leaf from a photograph. In any picture include a ruler. I would suggest putting the leaf on a white sheet of paper and a clear ruler below the leaf (as seen in the KBLOG photograph)