Bridges are one of the man-made wonders of our world, the physical feats of science, physics and engineering. The concepts of support and structure can be challenging for younger kids to grasp since they are often complex and combine various theories about weight, infrastructure and physics. Model bridges are a great way to introduce the fascinating ideas of engineering to younger children. By way of experimenting with design themselves, they can begin to learn what does and doesn't work in engineering, and start to understand the basic ideas of "why?".
Spaghetti bridges are perhaps the safest for younger children because they can break the spaghetti pieces into the sizes they need on their own. You will need to have glue on hand in order to hold pieces together (use a strong glue, not just white glue). Try wood glue or crafts glue. Kids will need to figure out how to make supports for the ends of the pasta to be held together. To make the pasta a little easier to work with, you can boil it for just a minute or two to make it slightly more flexible. But beware--the spaghetti will be hot when you take it out of the boiling water. You may be able to also use other types of pasta for the supports; try flat and smooth pieces such as the ends of farfalle.
Toothpick bridges are simpler, and best for younger children because they can use mini marshmallows to hold pieces together and just experiment. For older children, you can have glue on hand and they can figure out how to make supports and use such small pieces. Toothpicks can be broken into smaller pieces by hand, but these breaks are usually not smooth, so it is best to have an adult cut the pieces with a sharp knife and then give them to the kids.
Popsicle Stick Bridges
Popsicle stick bridges will be some of the strongest because the pieces are larger and more solid. Because of the solidity, it is easier to make larger bridges with different designs. Wood glue is the best way to hold Popsicle sticks together, and kids will have to figure out how to make supports. It may be best to use small pieces of Popsicle stick as supports. Or, kids can employ other materials as they see fit (cloth, clay, styrofoam). Again, to cut Popsicle stick pieces, you will need an adult to use a sharp knife for a clean cut. For an extra challenge, make kids use all full Popsicle sticks (or like materials) instead of giving them different size pieces. Organise competitions that judge based on how long the bridge is, how much weight it can hold, most aesthetically pleasing design, or the most creative.