Civil Engineering

Over the past few weeks, our young students have been immersing themselves in engineering. We have talked about what is considered technology and the roles of engineers, artisans and technicians.
Our study focused on a civil engineering project - building a bridge! We conducted some group research about different types of bridges and looking at how they handle under weight stress. Our demonstration looked at a beam bridge, a deep beam bridge and an arch bridge (though we did also learn a little about suspension bridges).

Beam bridges are easier and less expensive to build which is why we frequently see beam bridges crossing local (usually smaller) spans. However, of the three bridges we looked at, the beam bridge was the weakest in terms of supporting weight. The strongest of the three was the deep beam bridge which shares the general shape and function of a regular beam bridge but with additional support folded in to absorb some of the compression force.

Our house table teams then got to work following the Engineering Design Process: Ask, Imagine, Plan, Create, Improve. After gathering enough information to answer questions we had about how different bridges work, teams moved on to the Imagine stage and came up with lots of ideas for designing a bridge that would cross a 15 inch span, allow a toy car to cross it four times successfully, and support a significant amount of weight. Available materials included: paper clips, string, paper, tape, straws and craft sticks. Each material had an associated cost and the final price of each design was another element that would contribute to the group's overall bridge score.

From there, teams shared their ideas and collaborated on a final design plan. They listed the necessary materials and created a cost sheet to price out their bridges. Then we were finally ready to create! The bridges created by all teams were thoughtful and well constructed. Unfortunately, the next step in the process was to test each design...and we tested each bridge to failure.

Every bridge was built to be stable enough for the toy car to go across four times successfully! Our bridges had a varying range of penny weights it could support. But ALL of our bridges came in way over budget! We were glad the kids did not compromise safety to lower costs (though in truth we were not sure we would want to actually cross these bridges should a life-size version exist...).

The final step was for each team to reflect on how they could improve their bridge design. Did it need more support so it could hold more weight? Did it need more stability to keep it from wobbling (even if the toy car could make it across)? How could we maintain the successes of our bridge using different materials that would bring down the total cost of the bridge? Lots to think about.

As a final (and fun) exercise, we took all our new knowledge to create bridges across our little erosion gap by the 3-4 garden using materials we could find in our outdoor space. It has been fun to explore using science, math, and creativity to help solve problems! Check out pictures of our engineers and their bridges below.