Every enrichment project is designed to allow students areas of personal choice and ways to exercise personal strengths. Mr. Mc Donald's fourth grade class worked with Mrs. Siller, the enrichment teacher, studying wooden truss covered Vermont bridges.
       The main reference for this unit has been Spanning Time, Vermont's Covered Bridges by Joseph C. Nelson. In addition to detailed blueprints for the various truss designs, there are also beautiful pictures accompanied by historical narratives for all the remaining covered bridges in Vermont. Each student was provided with a copy of the history for a bridge that matched their choice of construction techniques for the balsa wood model.
       Secondary reference material included several books by Eric Sloan and an Internet article on the history of covered wooden truss bridges from a global perspective. The whole class worked together to highlight key information from this article that was needed to answer the research questions.
       Below is a brief description of the components of this project which were carried out in two weekly forty minute classes over a period of twelve weeks.

• Engineering Principles: This class explored the stability of squares, trapezoids, and triangles and the relationship of truss design to span length.
• Selecting a Truss Design: Students selected from a menu of materials and truss designs to create a 2D image of a specific truss.
• Research: Students were given a list of questions that would form the basis of a three paragraph written report. They were given all necessary resource materials to complete the research. Reports included information on the history of wooden truss designs and a specific Vermont bridge from Joe's book.
• Written Report: students worked simultaneously on the written report and model construction.
• Model Construction: students built balsa wood models to illustrate the selected truss design as practiced in Vermont with siding and roofing on one side only.

(Text provided by Joyce Siller)