Early Phase of the Program

Building a Bridge

1. Title of the Lesson: Building a Bridge

1. NJ Core Curriculum Content Standards addressed in the lesson.

• 5.1.12.B.1 (Logically designed investigations are needed in order to generate the evidence required to build and refine models and explanations): Design investigations, collect evidence, analyze data, and evaluate evidence to determine measures of central tendencies, causal/correlational relationships, and anomalous data.
• 5.1.12.B.3 (Empirical evidence is used to construct and defend arguments): Revise predictions and explanations using evidence, and connect explanations/arguments to established scientific knowledge, models, and theories.
• 5.1.12.D.1 (Science involves practicing productive social interactions with peers, such as partner talk, whole-group discussions, and small-group work): Engage in multiple forms of discussion in order to process, make sense of, and learn from others' ideas, observations, and experiences.
• 5.1.12.D.2 (Science involves using language, both oral and written, as a tool for making thinking public): Represent ideas using literal representations, such as graphs, tables, journals, concept maps, and diagrams.
• 5.2.E (Forces and Motion): It takes energy to change the motion of objects. The energy change is understood in terms of forces.

1. Identify Resources needed. (identify texts, equipment, media, family or community resources to be used in the lesson).
2. Teacher Use: Ruler, Tables or desks, pennies or other objects for bridge strength testing, container to hold pennies with clips to attach to bridge prototypes
3. Student Use: Toothpicks, gumdrops, scissors

1. Describe what students should know before they start the lesson.

• Students should be able to work cooperatively in small groups. They should listen to and have respect for others' ideas.
• Students should understand the steps involved in the engineering design process.
• Students should be able to draw force diagrams and to apply that skill to the bridge building task.

1. State the objectives of the lesson.

• Students will increase their ability to work cooperatively to solve a problem.
• Students will learn how to use a systematic approach to solving a problem.
• Students will learn about torque and how it relates to bridge design.
• Students will learn how to use the engineering design process to solve a problem.
• Students will learn that engineering involves using their ideas and knowledge to solve real-world problems.
• Students will learn about how to balance the cost of materials with the benefits they provide.
• Students will learn about civil engineering (building structures such as bridges), but also that other engineers are responsible for developing stronger, cheaper, or more environmentally friendly construction materials. Students will learn how the work done by engineers affects society for the better.
• Students will apply their knowledge of physics to solve a real world problem.

1. Identify important ideas in terms the subject area - describe in detail. Real life connections (make a list).

• The engineering problem-solving strategy (which mimics the ISLE cycle for experimentation) involves devising a series of possibilities that are tested and revised.
• The eight steps of the engineering design process are: identify the need or problem, research the need or problem, develop possible solutions, select the best possible solution, draw a prototype, test & evaluate, communicate the solution, and redesign.
• The engineering design process includes constructing a physical prototype: starting with plans and ideas, using materials to build the physical model. This prototype can then be tested, and the results applied to redesign and improve.
• Torque: Sum of (force * radius from pivot point). For a structure to be stable, not only must the sum of the forces exerted on it be zero, but the sum of the torques exerted on it must also be zero. When the building materials (gumdrops & toothpicks) can no longer provide a sufficient force and torque to counter those exerted on the bridge by the hanging penny container, the bridge will begin to break apart.

1. Describe potential difficulties students may experience with the content. Describe all formative assessments that you plan to use and how you will provide feedback.

• Students may have difficulty working cooperatively. One group member may dominate, especially boys in mixed gender groups.
• Students may have difficulty applying the engineering design process, rather than just employing a trial and error strategy. I will remind the students to plan ahead. Also, I can present the problem but not make the materials available for the first five minutes, which will force students to plan (steps 2-5) before building their prototype.
• I will monitor the groups, and make sure to engage group members whose opinions don't appear to be being listened to. This will demonstrate to the dominating group members that the others' ideas are to be valued. This also will ensure that all group members are contributing equally, and that all group members understand the successes and failures of their prototypes.
• I will ask groups what problems they are having, or what is standing in the way of their meeting their goals, to engage them in a discussion about the possible strategies they could employ to solve their problems, rather than just using trial and error. Students may need to be prompted to systematically change one aspect of their design at a time to solve the problem. I will ask students what assumptions they made in their initial plan that turned out to not be valid, and how they have revised their assumptions.
• If a group adopts a new approach, I will ask them to explain what they changed and the reason for the change. In addition, I will try to get them thinking about the physics explanation for the failure of their prior prototype.

1. Provide a description of the lesson including an agenda for the lesson.

• See handout attached at end of lesson plan

1. Time Table – who is going to be doing what and when during the lesson to make sure that students are actively engaged.

1. Describe the homework you will assign. What guidance will you provide the students?

• The homework will be for students to assess the strengths and weaknesses of their own design, and also that of at least one other group. and make at least one suggestion for a modification they could make that would meet a different need/ solve a different problem. This engages the students in the engineering design process. Discuss the homework the next day so students can learn from the ideas of others. Students will be instructed to think about how real world engineers apply the engineering design process to the construction of bridges, and which types of engineers might work together on the project. Students will also be asked to research one bridge that is famous for either being a novel success or being a failure (Tacoma Narrows). They will need to consider which types of engineers were involved in the design and construction of the bridge.

1. Teacher's Guide

• Make sure students are divided into effective groups. Group together students with differing strengths. Make sure all group members are actively participating.
• Make sure students follow the engineering design process and plan before building.
• Ensure that you are familiar with the materials and their benefits/ pitfalls.
• With the homework, make sure students think about how many different types of engineers might try to improve the bridge. Materials cost? More environmentally friendly materials? Bridge performance (strength) enhancement? And so on. Make sure a full class discussion of the homework assignment is included in a subsequent class period.

Building a Bridge

Goal: Design and build a bridge that meets the design criteria below with the largest possible strength to cost ratio (see below).

Design Criteria:

• The bridge must be at least 20” long and be able to span a gap of 12”
• Only materials listed below may be used.

Testing Criteria:

• Your bridge will be situated across a 12” gap between two adjacent desks. A cup will be suspended from your bridge. Pennies will then be added to the cup, one at a time, until any part of your bridge comes apart. The strength-to-cost ratio (the number of pennies in the cup/the cost of your bridge in $) will be calculated.

Available materials and cost:

Total number of pennies in cup before bridge breaks: ______

Calculation of Strength-to-Cost Ratio:

Number of

Pennies in Cup: ______= ______

Total cost:

Be sure to follow the Engineering Design Process and document your work:

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