With a partner, my secondary science methods students selected a tree and then combined their ample knowledge, creativity, and critical thinking and came up with several methods to determine the height of the tree.
Linda Dee and Karen Schedler were helping my students learn about Project Learning Tree (PLT) and its many science activities. My students now have the assignment to develop a lesson plan using a PLT activity and then teach a high school or middle school class using this lesson plan.
This class of students has already earned my respect for their knowledge, abilities, and great attitudes, but it was still exciting to see them apply what they know with their creativity and critical thinking. Indeed the process was just as important as the result. Their tree-height-measurement methods included (a) having a partner of known height stand by the tree and estimating how many of them it would take to reach the top of the tree; (b) measuring the shadow length of the partner and the tree and using ratios; (c) holding a vertical ruler up, with the partner at the tree, and using the marking of the ruler to determine ratios for the heights, and (d) comparing the tree height to a building and then counting brick segments on the building to determine height. Of course, if a protractor was on hand we could have used the distance from the tree, angle to the top of the tree, and some trigonometry to make this estimate.
The tree height estimates were compared to a value found by using clinometers.
These nifty devices, we were told, give a pretty accurate reading. You measure off 66 feet and look through the viewer with one eye and line up a horizontal line with the other eye. There were two scales for viewing the height of the tree, one in feet and the other in meters. In many cases, my students’ estimates were pretty close to the clinometers’ readings.
I was glad to see my students using metric measurements because we had talked about this before our spring break. My advice is to have their future students do all their measurements using the metric system and NEVER convert back into the imperial system. But with the “66 feet” distance and foot scale on the clinometer, it seems like our forestry colleagues, at least in the US, are not fully metrified. Prior to this, I had thought that the only people of science who were not completely immersed in the metric system were US meteorologists. It is obvious that some science traditions don’t change easily.