Javier Builds a Bridge A Civil Engineering Story
Learning Targets • Students will develop an understanding of the role of civil engineers in designing structures. • Students will discuss some of the problems, criteria, constraints, and solutions associated with designing bridges. • Students will identify steps in the Engineering Design Process.
Lesson 1 • Guiding Questions: • What is a civil engineer? • What things do you think a civil engineer might design? • Story is introduced: • Begins with a problem. • Brainstorming is done to solve the problem. • A prototype is built and tested. • Final product is made
Javier Builds a Bridge • Being a new stepbrother to little Luisa isn't always as much fun as Javier first thought it would be. When Luisa falls off the bridge leading to Javi's fort, his mother tells him they'll have to take the bridge down. • After some careful thinking, Javi realizes that he might be able to convince his parents to let him keep the bridge to his fort - if he can design a safer one.
Javier Builds a Bridge • With some help from his cousins and some inspiration from his little sister, Javi comes up with a new bridge design. • But will it pass the inspection of his stepfather, Joe, a real civil engineer?
Lesson 2 • Guiding Question: How do civil engineers prevent the pushes and pulls that act on a structure from making the structure fail?
Structure • What kind of structures do you think civil engineers work on? • Bridges are structures that are under extreme gravitational forces. • Beams that form the structure of the bridge are either under compression or tension. • Compressive forces squeeze the beams inwards while tension forces stretch the beams outwards. • The bridge is not moving so all forces acting on the bridge are balanced.
Forces • What kinds of things might apply a push or a pull to these kinds of structures? • http://www.pbs.org/wgbh/buildingbig/bridge/index.html • Compression: a pushing force • Tension: a pulling force • Torsion: a twisting force • Shear: two opposing forces acting on the same point
Suspension Bridges • Video • What forces caused the failure of the Tacoma Narrows Bridge? • What part of the Engineering Design Process was not addressed?
Three Little Pigs • Identify the pushes and pulls acting on the houses in the story. • How might a civil engineer solve the problem of the first and second pig’s houses?
Lesson 3 • Three Types of Bridge Structures • Arch bridge • Beam bridge • Deep-beam bridge • Basic components of all bridges: supports and span. • Different types of bridges are put together in ways to address the forces the bridge might need to withstand. • How much weight can each bridge support
Investigation • Make a model of an arch bridge, beam bridge, and deep-beam bridge • How much weight can each bridge support? • In what direction did the parts of the bridge move as it failed? • Can you think of any way to make the beam bridge stronger?
Lesson 4 • Guiding Question: How can we use our knowledge of forces, stability, different bridge types, our creativity, and the Engineering Design Process to design a strong, stable bridge?
Questions to Ask Yourself • How might you make your bridge stronger than just paper? • What are the different ways to support the span of a bridge? • How will you make your bridge stable?
Reflections • Do you want a high or a low score for your bridge design? • Which parts of your bridge design worked well? Why? • Which parts of your bridge design did not work well? Why do you think so? • Did any bridge designs fail in the same way? How did they fail?
Reflections • Were you able to improve your bridge design? • How did you decide what to improve? • Which step of the Engineering Design Process did you find the easiest? Why? • Which step of the Engineering Design Process did you find the most difficult? Why? • Which step do you think is the most important?
Designing a Bridge • Work in pairs • Review bridges tested • How could these materials be used on your bridge? craft sticks, string, tape, paper clips • Guiding Questions when designing your bridge
Guiding Questions When Designing Your Bridge • How might you make your bridge stronger than just paper? • What are the different ways to support the span of a bridge? • How will you make our bridge stable?