Building bridges is a student project that supplements lessons in math, science and art. Project guidelines and materials can be adjusted for a specific focus or modified to suit different age groups. Start your project with an appropriately detailed explanation of the physics behind bridge construction. This background serves as the basis for further exploration, and can include discussion of force and tension.
History is riddled with examples of failed bridges which have collapsed due to insufficient knowledge of architecture, building materials or environmental variables. Even though your toothpick bridge will not be under the same level of stress as a real bridge, studying the positive and negative traits of different bridges can help you make informed decisions about your own design. Look at videos and photos of bridges, talk about construction concerns and the variables that determine style, location and length. List the replicable features of successful bridges before planning construction.
Plan the toothpick bridge as if it were a real-world construction project. Set and honor limits for the project plan, such as a set number of toothpicks, bridge weight, minimum span or capacity. Draw a scale or full-size blueprint of the bridge. Use knowledge of bridges to predict weaknesses in the design. For example, a long, unsupported span will buckle under weight. Truss bridge designs are a common choice when building with toothpicks since they rely on small, angular elements.
Toothpicks come in a variety of shapes and sizes. Use thick, wooden toothpicks for construction as they have a larger area for glue application and are more rigid than their plastic counterparts. Choose round or flat toothpicks based on your design. A toothpick trimmer or utility scissors can be used to remove the ends of each toothpick. This makes the material less hazardous for children, lighter and more uniform. Wood glue is a preferable adhesive as it expands to fill gaps in porous surfaces and is designed to withstand stress.
All glued joints should be clamped and provided with sufficient drying time. Use paper clips or binder clips to secure joints while wet. If entering a professional competition, invest in toothpick holders, or plastic clamps specifically designed for toothpick construction. Build the main components of the bridge, such as the deck, towers and arch, separately to promote even drying. Weigh the bridge and pieces throughout construction to ensure that the guidelines of the assignment are met.