How to Host a Balsa Wood Bridge Contest

As with full-sized structures, building balsa bridges requires an understanding of physics.

Balsa wood bridge-building is a fun test of engineering skill, patience and teamwork. Contests to build these structures are held regularly in schools, colleges and business. They provide opportunities for adults to practice team-building skills, and when children are involved, the contests become a way of teaching them engineering skills, basic physics and static equilibrium. By bringing an element of competition to learning, participants are encouraged to outdo each other in their understanding of the necessary principles.

Things You'll Need

• Balsa wood
• Standardised weights
• Tape measure
• Wood glue
• Trophy

Instructions

1. Define the rules of your contest. Most competitions set a standard distance that a bridge must span and give a finite time limit to the building activities. They also establish a set list of materials that can be used; most often this is just balsa wood and commercially available wood glue. Decide whether the winning bridge will be the bridge that can hold the most weight, or the bridge with the best strength-to- weight ratio. You might also choose to set a maximum height or weight of the bridge structure.

2. Find a venue. You will need enough space for each team to have its own construction area, as well as a staging area where the strength of the bridges can be tested.

3. Establish who will be taking part in your contest. Invite people to form teams and establish a maximum number of teams. At this stage, if you do not have a captive audience (your school, for example), you might need to publicise the event with advertising. Circulate the rules to all who are planning to form a team.

4. Appoint judges: you will need help in ensuring that everybody is adhering to the rules and when checking the strength of each bridge. Ensure that each judge is aware of the rules you have decided on.

5. Hold your contest. Challenge each team to build the strongest bridge possible within the given time period, with only the materials allowed in the rules. Once the time period is elapsed, invite all the teams to watch as each bridge in turn is tested for strength by adding extra weight in small increments until it collapses. Also time the length of time the bridge can hold its load, as a tie-breaker. When all bridges have been tested, use the criteria you identified at the outset to determine a winner, and award a trophy.

Tips & Warnings

• If the contest is to be an educational exercise, design a lesson plan for before and after the actual contest. Explain how bridges are strengthened, and the properties of physics that impact on bridge design.

References

• Physics Balsa Bridge Building Contest: Rules and Regulations
• UAA School of Engineering: Balsa Wood Bridge Competition Rules