Lesson Plan Straw Bridge Design Challenge Grade Level Topics Covered Objectives Gr 4 and up Straw Bridge Design Challenge General: Students will work in teams to design and build a bridge using plastic straws and tape. (masking or scotch) The models will be tested by adding weight to them until they collapse. Grade-Specific Prescribed Learning Outcomes (BC Curriculum): SCIENCE: Processes of Science Grade 4: Make predictions, supported by reason and relevant to the content (Designing a bridge and predicting how it would do) Grade 5: Identify variables that can be changed in an experiment (Changing the shapes used to build the bridge, number of straws used, length of straws) Grade 6: Apply solutions to a technical problem (How would you improve on your bridge design? What geometric shapes could you use?) Grade 7: Create models that help to explain scientific concepts and hypotheses (Designing blueprint, making predictions, testing those predictions, reflecting on how we learn from mistakes/failures) MATH: Measurement and 3-D Objects and 2-D Shapes Grade 4: Describe and construct rectangular and triangular shapes (C4) Grade 5: Describe and provide examples of edges and faces of 3-D objects, and sides of 2-D shapes that are parallel, intersecting, perpendicular, vertical, horizontal (C5) Grade 6: Construct and compare triangles (C4) Grade 7: Perform geometric constructions (C3) Materials SWBAT (students will be able to): 1. Describe and design different types of bridges 2. Identify effective geometric shapes used in bridge design 3. Identify factors that civil engineers consider when designing bridges 50 plastic straws per team Tape for each team
Preparation Beforehand Scissors for each team Handout for each team Measuring tape/ruler 2 tables/desks that can be separated 30 cm apart A small paper/plastic cup or container and small objects that can be used as weight. Marbles are a good idea. Each marble can represent 1 car. Teacher Contact: - Use of tables/desks and scissors - The activity will align with the processes of science section of the Science IRP - It would be helpful if the teacher separates the class into groups of 3 befordhand Activity Preparation: - Gather the above materials and separate them into kits for each team. Background : Lesson plan was prepared by former civil engineer/now teacher candidate From the Internet: After the Industrial Revolution, bridges became more and more sophisticated as iron and steel became more commonly available. By using iron and steel, engineers could design bridges capable of supporting larger loads and spanning greater distances, making it possible to link cities and communities through shorter, more direct routes and crossing obstacles such as waterways or other natural features that had previously blocked passage. Sometimes we take it for granted that bridges provide important links between places. They enable us to get to resources, conduct commerce, travel, and visit other people. The design of bridges is important to the transportation networks we depend upon. Below information can be discussed at any time during the activity. It s optional and just extra information. Critical information is embedded into lesson plan. Connect the fact that while the materials used today will be different. The basic principles such as the geometric shapes used will be the same for our straw bridges as for the bridges we drive over everyday. Model making is extremely important for engineers. Would engineers build life-sized models of all their designs? (Of course not! Money and time!) Nowadays, most of the modeling is done using computers. The programs used to model bridges and buildings are actually very similar to the programs used to create 3-D animated films. However, sometimes it is still useful to build physical models and that s what we will do today! How much would bridges cost to design and build? A small pedestrian bridge crossing a creek could cost a few thousand dollars. The typical bridges we drive over that cross bodies of water would cost hundreds of millions of dollars. The most expensive ones cost billions of dollars. Port Mann Bridge = $2.46 billion Pictures and Example Bridge Designs at the end of this lesson plan
Introduction Identify 10 min - Introduce the concept of bridges. Why do we need N/A factors that them? What are they for? What are some concerns an civil engineer may have when designing a bridge? (e.g. engineers environment, cost, labor, weather, etc.) You could write consider down their ideas on the board when designing bridges -Ask them about bridges in Vancouver so that you are connecting with the world they know. What bridge connects and? Which bridge will I go over to get to? Which bridge is parallel to? (Linking to their community and math PLO s) Draw a picture like the following on the board to help explain instructions. - Today, we will be acting as a team of engineers making bridge models. We have been asked by the City of municipal government to create a bridge to cross a river. An amusement park is being built on the other side of the river and visitors need a way to reach it! Design objectives: You will be given 50 straws and tape and these are the only materials you can use to create your model.
It will have to span the river. The distance our model will have to span is 30 cm so make sure the bridge is longer than 30 cm! The river is the spawning area of many species of fish. Therefore, we should not disturb this river. No part of the bridge may touch the water! This means you can t have pillars supporting the bridge in the middle. You cannot tape your bridge to the desks/tables to help support it. To test your design, we will be adding weight to the bridge until it collapses. That means there has to be an area in the middle of your bridge where you can securely hold a small cup/container. How many cars can your bridge hold until it collapses? Your design should look like a real bridge. That means you should not just tape a bunch of straws together into a bundle. -Reinforce in students that taking risks and making mistakes are perfectly fine. Engineers do it all the time when building models and testing. We are not trying to find a winner in this activity. Part #1 Science in Bridge Building -Identify 15-20 Note to Volunteer: -Straw effective geometric shapes used min Tensile Strength is the maximum stress that a material can withstand while being stretched/pulled before failing/breaking -Optional: premade 2-D/3-D in bridge Compressive Strength is the opposite. shapes design Demonstrate Straw Power: (Optional Extension: This would be appropriate for higher level classes e.g. grade 7 and up) 1. Have two students come up and try to pull apart a straw. Discuss Tensile Strength if class is at that level. Otherwise, simply mention it is difficult to pull a straw apart. 2. Now, cut a short piece of the straw off. Demonstrate it is very difficult to push it inwards. Discuss Compressive Strength if class is at that level. Otherwise, simply mention it is
harder to crumple the straw if it is shorter. This concept applies to all materials! Look at the pillars and columns around your school. The shorter they are, the harder they would be to crumple. 3. Ask students to keep these concepts in mind when designing their bridge. Where would you want higher tensile strength? Where would you want higher compressive strength? Answer: Imagine loading a car on to a bridge. You would want higher tensile strength at the bottom of the bridge. You would want higher compressive strength at the top of the bridge. Go over Mathematics (Appropriate for all ages) Ask students what are some 2-D and 3-D shapes they know. These could be shapes they see in real life or shapes they have learned in math (connect to their math geometry unit and math PLO s) Which shapes would be better for constructing the bridge? Why? Lower-level children: Simply use the reason that some shapes (triangles, arches, X s, diagonal beams) would be stronger. They are sturdy. Higher-level children: These shapes can bear large loads without deformation. Distribution of forces: The forces are distributed equally and transmitted to the base.
Part #2: Design Blueprint (Pictures at end of lesson plan) -Describe and design different types of bridges -Identify effective geometric shapes used in bridge design 10-15 min -Give handout to students -Talk briefly about forming their engineering company and assigning roles to each person. They will need a president/spokesperson, civil engineer, and project manager. If they are in groups of 4, they can have more than 1 engineer or project manager. Have students think of a name for their company -Have students sketch a design of their bridge. As a team, decide on one design they would like to build. Handouts Volunteer should walk around and help guide their thinking. Do not correct their designs unless it would be impossible to construct it. Part #3: Building Models (Pictures at end of lesson plan) Same as previous 45-60 min -Handout materials (straws and tape) -Remind them that all students should help with the construction -The main job will be to keep the students on task. Let students know how much time they have remaining. (Write on board and tell them) - Straws - Tape Part #4: Testing Models (Pictures at end of lesson plan) Same as 15-20 previous min - Set up tables 30 cm apart - Gather students - IMPORTANT: Reinforce to students that taking risks and making mistakes are perfectly fine. Engineers do it all the time when building models and testing. We do this to find the best possible solution. We can learn from other people s models and designs. The results of our tests are definitely important but all designs, regardless of whether they held up a lot of cars, will teach us something important. It is not about which group built the strongest bridge; it is about learning about building bridges and model making. This is important because some students will inevitably only see it as a competition and will become upset if they lose. Other students may brag or make inappropriate comments if they win. - The above will be the default strategy. However, some teachers may want to make it into a competition with a winning design. Most cars = winner. In some classes, this could work. Please confirm with the teacher. -Container -Objects to add to container (marbles)
-Have 1 group come up at a time; introduce their companies and why they picked their design, predictions, etc. - Test models! If using marbles, put 5 marbles at a time. Have students count along. You may want to have a student hold their hands under the bridge to catch the container with marbles when it falls. Otherwise, you will have to pick up the marbles after every test. - For some designs without secure spots for the container, you may have to balance the cup using your hands. That s fine. The test is determining when the bridge will collapse, not when the cup tips over. (Tell this to the students so they don t think it s cheating.) Note to volunteer: With bridges designed by grade 4 s to 7 s, most bridges held between 20 and 120 marbles. You may want to set a limit where you only test up to 100 marbles. Outstanding designs could take ~200 marbles. Part #5: Closure Review 2-5 min - After results, ask them some questions. What was difficult about this challenge? What shapes did you find useful in designing a bridge? Why were some shapes better than others? What improvements could you make after having observed all the tests? - Praise students on excellent and varied designs. - Have students clean up all materials/floors (Confirm with teacher on how they want this to be done) Pictures: Designing
Building Testing
Example Bridge Models
Example Designs Used in Real Bridges