Session 8: “Design Challenge: Building a Strong Bridge”
Architect:
Syed Shayaan Haider - Markhor3D
Session Overview
In this exciting session, Grade 5 students will apply their understanding of structural strength and design principles to create a small bridge using TinkerCad. Working in groups, students will design a bridge that is 25 cm long, 6 cm deep, and 6 cm high, ensuring it can support weight effectively. They will consider various engineering factors such as arch designs, trusses, and material distribution to build the strongest bridge possible within the given constraints. This collaborative project encourages teamwork, creativity, and the practical application of engineering concepts, setting the stage for future projects like building a real bridge.
Learning Objectives
By the end of the session, Grade 5 students will:
- Apply Structural Strength Concepts: Use knowledge of thickness, supports, infill patterns, print orientation, ribs, trusses, fillets, and chamfers to design a strong bridge.
- Collaborate Effectively: Work in groups to brainstorm, design, and refine their bridge models.
- Design Within Constraints: Create a bridge that meets the size requirements (25 cm long, 6 cm deep, 6 cm high) and adheres to the material limit.
- Optimize Material Use: Learn to design efficiently by minimizing material waste while maintaining strength.
- Prepare for Future Projects: Gain foundational skills for more complex engineering challenges, such as building a real bridge.
Teaching Aids
Visual Aids:
- Demonstration Videos: Clips showcasing different bridge designs, including arches and trusses, and their impact on strength.
- Step-by-Step Guides: Simple screenshots or slides outlining the bridge design process in TinkerCad.
- Example Models: Display various bridge designs with annotations highlighting key structural elements.
- Infographics: Visual guides explaining efficient material use and the importance of different design elements.
Required Equipment:
- Computers or Tablets:
- One per group, with TinkerCad logged in and ready to use.
- Internet access for accessing tutorials and reference materials.
- Interactive Whiteboard or Projector:
- For live demonstrations of bridge design techniques in TinkerCad.
- Printed Examples:
- Physical models or images of different types of bridges (e.g., beam bridges, arch bridges, truss bridges) for inspiration.
- Notebooks and Pens:
- For students to take notes, sketch ideas, and plan their designs before modeling.
- Assistants or Volunteers:
- Additional adults to help guide groups through the design process and troubleshoot any issues.
Structure and Lesson Plan (Total Time: 60 minutes)
1. Introduction and Linking to Previous Sessions (10 minutes)
- Greet the Students:
- “Good morning, Grade 5! Today, we’re embarking on an exciting design challenge to build a strong bridge using everything you’ve learned so far.”
- Recap Previous Sessions:
- “Last session, you learned about what makes your 3D printed objects strong or weak. You designed a sturdy rectangle by adding ribs and fillets. Today, we’ll take those concepts further by designing a bridge that can support weight.”
- Present the Session Overview:
- “You’ll work in groups to design a bridge that is 25 cm long, 6 cm deep, and 6 cm high. We’ll focus on using efficient designs like arches and trusses, and ensure we use materials wisely to make the strongest bridge possible.”
2. Brainstorming Bridge Design Ideas (10 minutes)
- Explain the Activity:
- “Let’s start by thinking about different types of bridges and what makes them strong. We’ll brainstorm ideas for our bridge designs.”
- Provide Design Options:
- "Consider designs like:
- Arch Bridges: Use curved arches to distribute weight.
- Truss Bridges: Use a framework of triangles for stability.
- Beam Bridges: Simple and straightforward, using beams to support weight.
- Suspension Bridges: Use cables to hold up the bridge deck (more advanced)."
- "Consider designs like:
- Hands-On Brainstorming:
- “In your groups, discuss which type of bridge you want to design. Use your notebooks to sketch your ideas and note down the key features that will make your bridge strong.”
- Teacher and Assistant Support:
- Circulate the room to assist groups with brainstorming and provide examples or inspiration as needed.
3. Planning and Drafting Bridge Designs (10 minutes)
- Explain the Importance of Planning:
- “Before we start building in TinkerCad, it’s important to plan our bridge designs on paper. This helps us ensure our ideas are clear and meet the size and material constraints.”
- Provide Instructions:
- Step 1: Choose the bridge type from your brainstorming session.
- Step 2: Draw your bridge on paper, including all parts and features.
- Step 3: Add exact dimensions to each part, ensuring the overall size is 25 cm long, 6 cm deep, and 6 cm high.
- Step 4: Plan where you’ll add ribs or trusses and how you’ll use fillets and chamfers to enhance strength.
- Hands-On Activity:
- “Take a few minutes to sketch your bridge design with all necessary dimensions and structural elements.”
- Teacher and Assistant Support:
- Help groups refine their sketches and ensure all dimensions are accurate.
4. Introducing the Design Challenge and Material Limits (5 minutes)
- Explain the Design Challenge:
- “Now, it’s time to bring your bridge designs to life in TinkerCad. Your goal is to create the strongest bridge possible within the size constraints of 25 cm long, 6 cm deep, and 6 cm high.”
- Introduce Material Limits:
- “To make sure we use our materials wisely, each group is limited to using 150 grams of filament for their entire bridge design. This encourages you to design efficiently by minimizing material waste while maintaining strength.”
- Discuss Efficient Design:
- “Remember, instead of using 100% infill, use special designs like ribs or trusses and a reasonable infill density (20-30%) to make your bridge strong without wasting material.”
5. Designing the Bridge in TinkerCad (15 minutes)
- Explain the Activity:
- “Now, let’s start modeling your bridge in TinkerCad. Use the measurement and alignment tools to ensure your design meets the size constraints and is structurally strong.”
- Hands-On Activity:
- “Work with your group to build your bridge in TinkerCad. Focus on adding ribs or trusses, using fillets and chamfers, and optimizing your design to stay within the 150-gram filament limit.”
- Teacher and Assistant Support:
- Walk around to assist groups with their designs, offering tips on how to add ribs, trusses, fillets, and chamfers effectively.
- Ensure that all groups are adhering to the size and material constraints.
6. Evaluating and Refining Designs (5 minutes)
- Explain the Evaluation Process:
- “Once your bridge design is complete, review it to ensure it meets all the requirements. Check the thickness, supports, infill patterns, print orientation, and structural elements.”
- Hands-On Activity:
- “Evaluate your bridge design as a group. Make any necessary adjustments to improve strength and efficiency.”
- Discussion:
- “How did adding ribs or trusses help your bridge? Did fillets or chamfers make it stronger?”
7. Sharing Observations and Feedback (5 minutes)
- Invite Groups to Share:
- “Would any group like to share their bridge design and explain how they made it strong and efficient?”
- Provide Positive Feedback:
- “Great job on your bridge! The trusses you added make it very sturdy while keeping material use low.”
- “I love how you used fillets to smooth the edges of your bridge. It helps spread out the stress and prevents cracking.”
- Encourage Peer Feedback:
- “Listen to your classmates’ designs and think about what you liked and any ideas you might use in your own projects.”
8. Conclusion and Next Steps (5 minutes)
- Summarize the Session:
- “Today, you designed a strong bridge by applying what you’ve learned about structural strength and efficient design. You used ribs, trusses, fillets, and chamfers to make your bridge durable while staying within the material limits.”
- Preview Next Session:
- “In our next class, we’ll prepare your bridge designs for printing, ensuring they are ready to be turned into real objects.”
- Closing Encouragement:
- “Keep thinking about how to make your designs strong and efficient. Excellent work today, everyone!”
Glossary
- Structural Strength: How strong an object is and how well it can hold up without breaking.
- Thickness: The measurement of how thick the walls of your model are. Thicker walls are stronger.
- Support Structures: Extra pieces added to hold up parts of the model that hang in the air during printing.
- Infill Patterns: The internal structure of your model that affects its strength and weight.
- Infill Density: How much of the inside of your model is filled. Lower densities use less material but can be weaker unless special designs are used.
- Print Orientation: The way you position your model in the 3D printer, which can influence its strength.
- Ribs: Thin, sturdy supports added to the design to increase strength without using much material.
- Trusses: A network of small triangles added to the design to provide strength and stability.
- Fillets: Rounded edges that help spread out stress and prevent cracks.
- Chamfers: Beveled edges that also help spread out stress and add strength to parts.
- DFAM (Design for Additive Manufacturing): Guidelines to design 3D models that print successfully and are functional.
- Extrusion: The process of adding height to a 2D sketch to create a 3D object.
- Precision: The quality of being exact and accurate in measurements and design.
- Pivot Point: The fixed point around which a part rotates or moves.
- Rotational Motion: Movement in which an object rotates around an axis or pivot point.
- Layer Lines: The visible lines on a 3D printed object that show where each new layer of plastic was added.
- Top Layer: The very last layer printed on an object, which can affect its finish and appearance.
- Bottom Layer: The first layer printed that adheres to the print bed, important for the object’s stability.
- Scaling: Changing the size of an object while keeping its proportions the same.
For suggestions, improvements, and corrections, feel free to reach out at shayaanhaider@gmail.com