Expansion and shrinking of wood
The hypothesis that wood expands along the growth rings when humidity is high and shrinks when humidity is low, is proven to be true.
Dried wood is much easier to work with compared to freshly cut green wood. The removal of moisture from the wood makes it lighter and easier to handle. Storage, handling and shipment costs are also cheaper because they are lighter. Dried wood also expands and shrinks less, and therefore is easier to be fastened securely using bolts or nails. It is also easier to cut with precision. As the wood dries, it strengthens.
To improve the reliability and accuracy of our results, a larger number of wood samples should be used.
This science fair project may be repeated, this time, with other types of woods like Pine, Fir, Hemlock or Birch.
Modify the science project experiment, using different levels of humidity in a humidity chamber and comparing the rate of expansion for each type of wood.
Wood movement - http://www.woodworkerssource.com/wood_movement.php
Allowing for expansion and shrinking - http://woodworking.about.com/od/dealingwithproblems/p/expansion.htm
Be careful when removing the hot wooden blocks from the oven. Use gloves to protect your hands.