Building a model bridge is one way to learn about bridges---how they work, and what they do. Model bridges are usually built out of balsa wood, but can be built using toothpicks just as well. The model bridge doesn't have to be a complex network of toothpicks capable of withstanding added weight. A simple, beam bridge made of toothpicks will work just as well.
Figure out exactly how long you want to make your bridge. For example, if you want your bridge to span a gap of about 6 inches, you may want your bridge to be at least 12-inches long.
Place enough toothpicks side-by-side to go the length you want to cover with your bridge. Remember that the standard toothpick is 1/16-inches wide by 2.5-inches long. If you are building a 12-inch bridge, for example, you would need 192 toothpicks.
Apply multipurpose glue to each toothpick in order to attach it to the next toothpick side-by-side. This will make the deck of the bridge. Allow time for the glue to dry.
Attach a toothpick perpendicularly to the toothpicks that creates the deck of the bridge using multipurpose glue. Attach this toothpick about 1-inch in from either end of the deck and about 1/4-inch from the edge. Repeat this step until you have a toothpick attached perpendicularly along both edges of the bridge, from end to end. If you are building a 12-inch bridge, you'll need to attach eight toothpicks to do this.
Place your toothpick bridge over the gap you were meaning to span with it.