The Bridge Building

Hey, Bonnie here! So far this year, we have completed four modules in eighth grade PLTW. We are currently working on our fifth (for me it is mechanical systems). The third module I did was engineering. For the engineering module, we had two different challenges. The first challenge, (which was independent) we had to watch a video and contribute our ideas on a class board. The second challenge, we had to create and build a bridge out of limited materials.

The first step we had to do, was we had to write a design brief. A design brief is the “blueprint.” What I mean is, it is a basic list that tells you what the problem is, what the constraints are, and what needs to be solved (solution). Our blog post pic 1problem statement was we had to build a bridge that is made out of toothpicks, glue, and thread. The constraints that we had was we could only use the given supplies, it had to be at least sixteen inches long, the height had to be four inches tall, the width of the bridge also had to be four inches, and it had weigh at least forty grams. The bridge had to be able to bear some weight.

After we completed the design brief, we had to do another thing before we could start building the bridge. We had to create a decision matrix. A decision matrix is a table that has all of our possible blog post pic 2ideas for the project. We had the criteria for the bridge we needed to build. For each of the ideas we had, we would have to rank how well it met the criteria and then total the points up. Which ever idea had the most points, would be the best choice to build.

The last step we had to do before we could build the bridge was draw a technical drawing for our idea. All the drawing required was that it had toblog post pic 3 show the basic structure and it had to have the measurements. This was just a drawing of our idea, so it exactly what our bridge looked like because as we were building our bridge, we changed the design a bit to make it better and stronger.

Once everything was ready and we had a plan, we started to build our bridge. The first thing we decided to do was to create different jobs for everyone, so that we could manage our time better. We also made a plan so that we knew what part of the bridge we were supposed to be working on. At first, we were using a lot of string to support the bridge, but then we realized that the bridge wasn’t getting any stronger. It turns out, we needed to use a lot more of the toothpicks than string. After we build all the parts of the bridge, we had to figure out a way to connect them. This took awhile, since we had used so much string and we couldn’t really find a place to connect each piece to one another.

Once we had completed building our bridge, it was ready to be tested. To test our bridge’s strength, we had to tie two strings to a board. We the had to put the two strings over our bridge and lay our bridge on two stools a distance apart. There was several small weights that we put on the board to see how much weight our bridge could hold (in grams). Our bridge held up around 1,200 grams, which was a lot more than what we expected.

So this was the first module that was really hands-on that I have done. It was a good experience because after my group and I completed the challenge we were all proud. For me, I felt accomplished because it was difficult and frustrating at times. The one thing that I think was the hardest about this challenge was trying to keep the toothpicks together, using only elmer’s glue. But, I had a lot of fun building this bridge and I can’t wait to do more of these modules!

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