This project involves careful use of resources above all else, to introduce the concept of good stewardship and efficient design, defined as the bridge design which can hold the most weightusing the least materials. This lesson is recommended for smaller class settings, but you can break larger classes into smaller groups just as well. This project allows you to provide hands-on instruction for individual students or groups of students as they construct the bridges. Discuss with the students the strategies of simple, effective construction techniques. Discuss budgeting of resources, green building practices (especially how to plan the cuts to minimize waste), and situations where renewable resources may be substitutes for traditional resources. Students should also observe that reduced overhead does not necessarily equate to reduced quality of products.

Towards the end of the final session, the instructor holds a "weigh-in ceremony" in front of the students, where the capacity of each bridge is measured. Expect some well-built bridges to actually explode when they break, meaning they fail all at once under incredible tension. Then the instructor will hold a ceremony after all bridges are finished with the testing. Give a prize to the overall winner or have categories, such as best looking design, longest bridge, strongest bridge, etc. and give prizes for each.

Pitsco Balsa Bridge Kits, “structural shapes and forces” manuals, green wood glue, sandpaper, timber cutters, Exacto knives, foam core boards, wax paper, straight pins, pliers, cardboard, 5-gallon bucket, water pitcher, weight gauge, paper, prizes (optional)