Stimulating Understanding of Computational science through Collaboration, Exploration, Experiment, and Discovery for students with Hearing Impairments
a collaboration of the Shodor Education Foundation, Inc., Eastern North Carolina School for the Deaf, Barton College, the National Technical Institute for the Deaf, and Interpreters, Inc.

For Teachers!

How to weigh a tree

This page has links to help you download the models used in this module.

This page contains the materials used in this lesson. If you click on the instrument, it downloads to your computer. If you use them in lessons you design, please reference them so other teachers can find the material and mix and match like you have. 

CO2 Calculator This is an Excel spreadsheet. The spreadsheet calculates a tree's diameter from its circumference, height from 3 similar triangle measurements, tree's green weight from height, diameter and tree type, roots weight, total weight, Dry tree- root and total weight, Carbon in tree - root and total tree, CO2 in tree - root total tree, equivalent CO2 from gasoline - natural gas - electricity - heating oil.

CO2 Calculator Mac This is a version of the calculator described above that doesn't use sliders for input so it will run on Macintosh computers.

Dry weight - percent moisture comparison. This is an Excel spreadsheet that compares the dry weight of different kinds of trees with their percent of moisture. There isn't an obvious trend. Many questions don't give us the answers we expect. Since there isn't a pattern we should ask why not. If trees become completely saturated with water they sink. The reason they float is that the heartwood is dead and the cells have "air" in them. When these balloons fill with
water the log sinks. The percentage of water relates to the percentage of cells that have water in them and how much water these cells contain. The dry weight of a tree is related to the ratio of cell wall to empty space in the cell. In dry weight the dominant factor seems to be the percentage of cell that are filled with water. There is a slight trend for heavy trees i.e. trees with relatively thick cell walls to interior ratios, to have less water. All other things being equal, that makes sense, but most of the time the other things aren't equal. It is good for students to see that scientific explorations don't always proceed directly to the expected results. Even unexpected results are opportunities to gain insight.

Tree diameter This is a web page that contains a JavaScript calculator to calculate a tree's diameter if you input its circumference. 

Tree height This is a web page that contains a JavaScript calculator to calculate a tree's height using similar triangles. You input distance to tree, distance from your eye to ruler, and apparent height of tree against the ruler. The calculator returns an estimate of the tree's height.

The following links are to web page calculators that return the green weight for their respective types of tree:

Yellow Poplar 

Sweetgum

Soft Hardwood

Hard Hardwood

Southern Pine Coastal

Southern Pine Piedmont

Web page that calculates the dry weight of a tree based on its green weight and moisture content.

The following are tables used to calculate the weight and dry weight of trees:

Table of tree type i.e. pine soft or hard hardwood

Table with percent water in green wood and dry/green ratio.

Developed by
The Shodor Education Foundation, Inc.

Copyright © 1999-2001 by The Shodor Education Foundation, Inc.

This project is supported, in part, by the National Science Foundation Opinions expressed are those of the authors and not necessarily those of the National Science Foundation.