Grade Level: Elementary school
Time Required: 3 hours (wild guess!)
(three 60-minute class periods)
(three 60-minute class periods)
Subject Areas: Life Science, Physical Science, Problem Solving
Maker Challenge RecapIn this maker challenge, students use the engineering design process to design a bridge out of silkworm cocoons that can hold at least 50 grams. Students can use other materials to supplement the silk bridge, but have a $10 budget. Students evaluate proposed solutions that best meets the above requirements, build and test prototypes, revise and improve their designs, and report their findings to the rest of the class.
Maker Materials & Supplies
- silkworm cocoons, available online (boil, cut, and distribute the silk to each group ahead of time)
- supplemental materials to build the bridge such as paper, craft sticks, and rubber bands (have a variety available for students to choose from if desired)
- fabrication tools and adhesives such as scissors, glue, and masking tape
- sturdy books (such as textbooks) to support each end of the bridge
- poster paper and markers
- metric weight set (1 g, 5 g, 10 g, 20 g)
- lab notebooks and pens
- copies of the Silkworm Strength Supply List
Worksheets and AttachmentsVisit [ ] to print or download.
More Curriculum Like This
Students are presented with a brief history of bridges as they learn about the three main bridge types: beam, arch and suspension. They are introduced to two natural forces — tension and compression — common to all bridges and structures.
Silk is a natural protein fiber used to make many different materials. Silk fiber is so strong that manufacturers use it in bicycle tires, clothing, bedding, surgical sutures, parachutes, and furniture. Because of silk’s strength and antibacterial properties, doctors and nurses use it for wound healing. Silk often comes from the cocoon of the mulberry silkworm (Bombyx mori), which eventually turns into a domestic moth. These cocoons are soft, lightweight, and smooth, but also are incredibly strong when heated. How else could you used silkworm cocoons?
Now, let us talk about a human-made structure made by civil engineers: bridges. It is important for bridges to be extremely strong so people, cars, or trains can cross over them. Civil engineers plan, design, and oversee construction and maintenance of building structures, such as bridges. Can we learn about the structure of bridges by studying the strength of things in the natural world, such as silk and silkworm cocoons?
Since silk and cocoons have proven to be extremely strong and durable, your task is to take on the role of civil engineers and use the engineering design process to prototype a bridge out of silkworm cocoons that can hold at least 50 grams. Just like engineers, you will also have to work within a budget; you will have $10 for other materials besides the silk. You will also conduct research on ways engineers build bridges so they are strong and durable, evaluate proposed solutions that best meets the requirements, build and test prototypes, revise and improve your designs, and report your findings to the rest of the class.
- Purchase your supplies, but keep within a $10 budget.
- Get approval for your prototype; sketch and design the prototype in a lab notebook for the group.
- Make sure to use 15 cm of silk in your design
- The bridge must be 30.5 cm in length.
- The bridge must support 50 grams.
- Refer to the Engineering Design Process hub on TeachEngineering to guide your students through the challenge.
- Consider reading “Silkworm Facts for Kids,” which includes the life cycle and history of the silkworm and silk from the cocoon.
- Before the activity, consider reading the books, Silkworm or The Story of Silk.
- Show images of different types of bridges, including suspension, arch, truss, beam, etc. and discuss what makes these bridges so sturdy. Students can also conduct research on their own to get ideas about their own prototypes.
- Consider watching the video “What Makes Bridges So Strong” by SciShow Kids to engage students in the engineering portion of bridge building.
- Encourage students to document their work in their lab notebooks or through the use of a design journal.
- Create groups of 2-3, based on student and classroom needs.
- Allow students to research different types of bridges, including what makes them strong, in the library or using class computers. They should also research silk and silkworm cocoons to see how silk can be so strong. Instruct students to write their research down in their lab notebooks so they can use it to help design their prototypes.
- Give students the amount each material costs and distribute copies of the Silkworm Strength Supply List. (Consider adjusting the document according to grade.) They cannot exceed $10. Have students record their budget, their purchases, and the amount of money remaining in their lab notebooks. Provide each group with the supply list attached to view the prices. Groups should draw their prototype that they would like to design in their lab notebooks, complete with appropriate labels and explanations of materials. Let students know that they must use at least 15 cm of silk.
- Start by giving groups two textbooks. Have the groups use a ruler to place the books 30.5 cm apart. Guide students to build their bridges. When they groups finish their initial design, have them test their bridges by placing a 50-gram weight in the center of their bridge. If the bridge does not support the weight, use smaller gram measurements to see how much weight it holds, and then have them redesign until it can hold 50 grams. If the design does hold 50 grams, tell the group to change their design to see if it can support even more. Remind students that they should learn from their failures and encourage them to use new materials to alter their solutions for new designs. Each time they change their designs, they can receive extra money or trade in materials (at your discretion); they must also draw their new ideas and design in their lab notebook before attempting a redesign.
Give each group one piece of poster paper and markers to present their design to the rest of the class. Students should focus on the following aspects on their poster:
- The challenge and/or problem: “can we design a bridge made out of silkworm cocoons and other materials that supports at least 50 grams?”
- A drawing of their final design.
- What they changed in each design phase.
- What they learned from failed tests of certain materials and designs.
- If the silkworm cocoon helped what made it so strong.
- How much money they spent and why budgeting matters in engineering.
Finish with a discussion on how the silkworm cocoons’ strength aided in their bridges’ designs.
- While circulating and guiding the students through the design process, make sure they are recording everything that they are doing in their lab notebooks. If needed, have a mini lesson about documenting in lab notebooks beforehand.
Copyright© 2019 by Regents of the University of Colorado; original © 2019 University of Florida
Supporting ProgramMultidisciplinary Research Experiences for Teachers of Elementary Grades, Herbert Wertheim College of Engineering, University of Florida
This curriculum was based upon work supported by the National Science Foundation under RET grant no. EEC 1711543— Engineering for Biology: Multidisciplinary Research Experiences for Teachers in Elementary Grades (MRET) through the College of Engineering at the University of Florida. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.
Last modified: December 12, 2019