The student will compare possible solutions to best address an identified need or problem. Design and construct a solution to an identified need or problem using simple classroom materials. Overview Building Bridges Scavenger Hunt Complete the Chart Comparison on bridges using the following website: http://www.pbs.org/wgbh/buildingbig/bridge/index.html From this site go to the links of individual bridges. Building Bridges Vocabulary Worksheets Access the following website to do the virtual experiments: http://www.pbs.org/wgbh/buildingbig/lab/forces.html Do the virtual experiments as well as see real life examples. Access the following virtual bridge-building site to construct the correct type of bridge for a specific area: http://www.pbs.org/wgbh/buildingbig/bridge/challenge/index.html Do the virtual activities as well as see the correct type bridge for certain areas. After you have worked through the worksheets and the websites, draw a diagram of your bridge on graphing paper prior to construction. The Cause… Way Essay Build your bridge. Turn in your Bridge with a paper that contains your actual costs. Have a contest to see which bridge holds the most weight. Due Dates: January 7th Activities January 9th Diagram of bridge January 16th The Cause… Way! Essay January 28th Bridges with written paper and the Worksheet February 2nd-3rd Bridge Competition IMPORTANT! This is done at home. There will be no class time available to work on it. Manage your time wisely! The due dates will come fast. DO NOT PAINT THE BRIDGES! Activities 1. Building Bridges Scavenger Hunt 2. Building Bridges Comparison Sheet 3. Building Bridges Vocabulary Activity 1 Building Bridges Scavenger Hunt Directions: Use the following websites to complete the information. www.pbs.org/wgbh/nova/bridge/meetarch.html www.pbs.org/wgbh/nova/bridge/meetbeam.html http://www.pbs.org/wgbh/nova/bridge/meetsusp. html www.pbs.org/wgbh/nova/bridge/meetcable.html www.tfhrc.gov/pubrds/summer95/p95su23.htm www.howstuffworks.com/bridge.htm Activity 2 Building Bridges Comparison Sheet Use the following website to complete comparison: http://www.pbs.org/wgbh/buildingbig/bridge/i ndex.html Activity 3 Building Bridges Vocabulary Use the following websites to define the vocabulary words. www.pbs.org/wgbh/nova/bridge/meetarch.ht ml www.pbs.org/wgbh/nova/bridge/meetbeam.h tml www.howstuffworks.com/bridge1.htm Bridge Diagram Draw a picture of what you think your bridge is going to look like. Doesn’t have to be the end product. Can change as you find that it doesn’t work You find better ways The Cause...Way Essay Scenario: You are the mayor of your town, My City, USA. The residents who elected you are angry because the town needs a new bridge to cross the Windy River. The town does not have the money from taxes to pay for the bridge, and attempts to raise the money from local businesses have failed. There is an upcoming election in the fall and you want very much to be reelected as mayor of My City. Your must find money to build the bridge My City so desperately needs. Your last chance is to lobby before your state government and convince them to allocate the funds for the bridge reconstruction. Write a persuasive and convincing proposal to accomplish the goal - My City will get its bridge and you will be reelected! The Cause… Way Essay 1. Why the bridge is crucial to My City Writing Lengths a. How the bridge is used most (‘real life’) At least these lengths 2. How long it will take to build (‘real life’) 1. ½ page 3. What material you propose to build the 2. 1 Paragraph bridge from (‘real life’) 3. ½ Page 4. Budget Prediction (model) 4. 1 Page Total a. Man hours a. 1 Paragraph i. You ii. Anyone that helps you out b. 1 Paragraph b. Materials c. ½ Page (See Worksheet) c. Show the math (worksheet format) 5. 1 Page 5. Design (model) 6. 1 Page a. Written Description i. What the bridge should look like Formatting b. Why the bridge appearance is important Font or unimportant (‘real life’) Arial 6. What will happen if the bridge isn't rebuilt Size 12 (‘real life’) a. Economy Double spaced b. Social c. Alternatives if the bridge isn't built Worksheet Fill this out as you build the bridge. Keep track of: Time spent Glue ○ 4 fl oz bottle size Floss ○ in inches Popsicle stick ○ Used and wasted Worksheet You Helpers Start Finish Start Finish Time Time # of Hours Time Time # of Hours Total Total Sign-Off Bring this to class. Teacher will sign it so that you can keep track of what you have done. Sign-Off Teacher Initial Activity 1 Activity 2 Activity 3 Diagram Essay Bridge with paper Rubric 5 10 15 20 Bridge is unattractive, The bridge is structurally The bridge is structurally Bridge appears to be a weak, inappropriate or sound and attractive, but sound and attractive. It Layout/ Design basically an unsound structure that doesn't fit may not hold the weight of supports weight and fits specifications. structure. others. specifications. Following Bridge Few of the bridge Some of the bridge Most of the bridge All the bridge guidelines Guidelines guidelines were followed. guidelines were followed. guidelines were follwed. were followed. Information researched Information is accurate Some information is Information/ and written about bridges provided, but is limited or Information is well written and complete, is Essay is poorly written, and interesting to read. creatively written, and is inaccurate. inaccurate, or incomplete. cleverly presented. The activities poorly Some of the activities are Most of the activities are Activities are accurate Activities written, inaccurate, or done, but is limited or done, but some and complete. incomplete inaccurate. inaccuracies. Bridge Guidelines Materials Popsicle sticks ○ Regular size ○ No Jumbo sizes Dental floss White glue ○ Water soluble white Elmer’s glue. Yellow wood glue or glues containing resin additives or other cement binder is not allowed. DO NOT PAINT THE BRIDGES! Bridge Guidelines Weight The bridge must weigh 400 grams (approx 1 lbs) or less. Bridge Guidelines Dimensions The clear span (distance between supports) of the bridge must be 18 inches in length. (18.5 in. ≤ 24 in) No part of the bridge may exceed 8-inches above the end supports or 3-inches below the end supports. The bridge must have a 4-inch wide roadway. No part of the roadway may exceed 1-inch above the end supports. Bridge Guidelines Roadway The roadway must be constructed as if wheeled traffic were to cross over its span. The roadway must be continuous along its width over the entire distance between the supports. No gaps shall exist in the roadway except where natural warping has occurred after construction of the bridge. The roadway at the midspan is the portion of bridge to be loaded. If you have bridge structure over the roadway, at least a 3-inch square opening must be maintained above the midspan loading area on the roadway to allow the bridge to be loaded. The roadway must be constructed such that a truck 4-inch wide and 4-inch tall could pass over it. Final Write Up When you turn in your bridge, you will turn in a ½ page paper with the following: Budget ○ Meet or Exceed? ○ Man hours You Anyone that helps you out ○ Materials Worksheet Helpful Hints Why Popsicle Sticks? Why Popsicle Sticks? Popsicle sticks are imperfect. Some may be bent, warped, or knotty; while others may be brittle, thin, or cracked. Visual inspection will weed out grossly deformed sticks, but students must deal with the slight imperfections present in all sticks. This is true in the real world where perfect materials are not available and careful thought must be given to the reliability of the construction materials. Engineers must attempt to quantify and account for deficiencies in both initial and post-construction material properties. Popsicle sticks are limited to a standard size which falls short of the overall bridge dimensions. In order to span a distance of 24 inches, a minimum of six sticks must somehow be connected together in a straight line. Again, this reflects real design problems where materials are finite in dimension and must be assembled in some manner to meet the engineer’s needs. By being limited to only two allowable materials - wood popsicle sticks and white glue - students will need to use creativity, ingenuity, and resourcefulness in order to maximize the strengths and minimize the inherent shortcomings of each material. Tips for Bridge Building Definitions: A member is any portion of a wooden popsicle stick used in the construction of the bridge. A whole stick, half a stick, or even a segment of a toothpick- sized stick are all considered members. 1. Always start with paper and pencil first. Sketch out your ideas. Draw your bridge in at least two views - looking at it from the side and looking at it from the end so you get a good idea of what you’re building. 2. Choose the design you are sure you can build. Are you confident your bridge will meet all the rules? Try using the West Point Bridge Designer at http://bridgecontest.usma.edu/ 3. Think about how the load will transfer from the 3" x 3" area in the middle of the bridge, through the structure and out to the supports at each end of the bridge. Not all parts of your bridge will have the same load running through them. What bridge members do you think will take the greatest load? Make those members stronger. 4. Which members do you think will be in compression? Which ones will be in tension? A single popsicle stick in tension can hold more weight than one in compression which will buckle and snap. Make sure your compression members are strong. 5. Your bridge members are only as strong as your connections, so pay special attention to the connections! How can you construct strong connections? Drilling or notching the end of bridge members is allowed. 6. If your bridge has similar patterns that are repeated throughout your design, construct modules so the pattern is accurately constructed each time. If your pattern is not dimensionally consistent or each side of your overall bridge is not symmetrical, some parts of your bridge will take more load than you originally planned. 7. Before you build your entire bridge you may want to test small parts of your bridge and compare one design to another to see which is stronger. You can even test your stick connections. How can you make a stronger stick connection? 8. If you design a truss, be sure it extends all the way to the ends where it will be supported. Don’t put a truss just in the center section. 9. If you use several rows of sticks to make up a member, don’t leave any sticks out or the member probably will fail at that point. 10.Lateral supports (members that are perpendicular to the direction of traffic on the bridge) are important, but the majority of the strength is need in the main members spanning the 18 inch gap (members that are parallel to the direction of bridge traffic). 11.Your bridge is loaded on a 3-inch by 3- inch square on the roadway. Be sure to reinforce that square and allow for the load to reach the rest of the bridge. 12.Be sure to make strong connections between the roadway and the main members spanning the 18 inch gap. You don’t want your roadway to fail before your main members are loaded up. 10.How does your bridge look? If this were a real bridge, do you think the public would find it pleasing to the eye? Can you make your bridge attractive and strong at the same time? 11.Construct a bridge on a surface that glue will not stick to! Try to work in an area you don’t mind getting messed up. 12.Plan ahead!!! Don’t wait until the night before the contest to finish the bridge! (Wet or damp glue doesn’t work very well.) Tools to help you with your bridge construction pencil paper wire cutters for cutting sticks Exacto knife clips, rubber bands, and weights to clamp pieces together when the glue is drying and finally, ........ PATIENCE !!! (Good bridges take time to build.) IMPORTANT! This is done at home. There will be no class time available to work on it. Manage your time wisely! The due dates will come fast. DO NOT PAINT THE BRIDGES!
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