Prerequisites
In previous lessons, students should have familiarity with the concepts of “force” and “mass”.
Lesson note: This task focuses on a specific current event surrounding a natural hazard event in Nepal. Alternatively, this task could be done around a local natural hazard. What are some natural hazards they might encounter in their own local environment? Examples will vary depending on where students are, but may include severe weather, flooding, tornadoes, hurricanes, etc. Ask students to consider if there would be communities in their own area that may become isolated when natural hazards hit? How would we get supplies to them? This may change some of the criteria and constraints of the design, but would largely follow the same format included here, and would address the same PEs, DCIs, practices, and CCCs.
Driving Question: What components and materials can be used to create a model chair lift, designed to carry a set of aid materials?
Alternative driving question: How can we carry supplies to a remote village that is cut off because of the impacts of a natural hazard?
Investigation 1: Introduction to the Challenge
Materials
- Image or video of a ski lift
- For each group: Ping-Pong ball, string, floral wire, pipe cleaners, bendable aluminum wire, straws, paper towel tubes, paper clips, tape, balloons, glue, string, foil, plastic wrap, pulley, other items available in the classroom.
Instructional Sequence
Defining the problem: Earthquake relief
Begin the lesson by discussing the recent earthquake activity in Nepal, which resulted in catastrophic human impacts (note: the context included here deals with a particular relevant current event, but feel free to change this context to a more relevant context if appropriate). Depending on the interests of your students, you may want to spend a little extra time discussing the earthquake and its impacts itself, to create a collective interest and to lead into the specific problem to be addressed in this lesson.
Some sample topics may include:
- How much of Nepal was affected?
- How many people were affected?
- What were the direct impacts of the earthquake on people in the area?
- What were the direct impacts of the earthquake to the area? Do these impacts have further indirect impacts on humans on in the area?
(Possible extension activity: have students conduct a research project on earthquake prevalence in the region, including the causes of the earthquake activity, possible predictions of future earthquakes, and predictions of impacts on organisms in the area)
As students share their ideas, record them as a class. Based on their ideas, ask students to focus specifically on human impacts, asking them what kinds of problems may have arisen for humans as a result of the earthquake activity? Use this discussion as an opportunity to introduce students to the idea that there are villages in the mountains of Nepal. Ask students to gather information from reliable sources to describe what the impacts of the earthquake were on these villages. (note: depending on student experience with information gathering from sources, they may need additional support regarding the evaluation of reliable sources, and determining whether the information they are gathering is relevant and sufficient for describing the impacts of the earthquake specifically on these village populations.)
Ask students to share their findings with a small group of peers. As you walk around, guide students to think about what core problems are facing village populations (e.g., lack of access to food and clean water; disruption of roads/access; limited medical supplies). In their groups, ask students to represent their findings from their research in terms of a model (e.g., diagram, concept map) of the system. In their groups, ask students to use their system model to identify 1) the causes of the impacts on the villagers, 2) similarities and differences in the causes and effects represented in their system model. As you walk around the room, encourage students to think about multiple causes for a given effect (e.g., for an effect of limited medical supplies, causes may include limited road access, increases in the injured people in an area, inability to predict the need of so many medical supplies, etc.), and whether there are any common solutions that may address multiple problems. Ask students to share out the collective findings of their group. As a class, consider how this village system (including the problems they face) is different from populations that are not in the mountains. Use this conversation to help students think about whether materials can easily get to the mountain populations.
Ask students to use their model of the mountain village system to consider this question, annotating which problems/interactions within the system may arise from limited ability to deliver materials, and which problems would be mitigated with an appropriate solution. Ask students to think about what the major features a solution that addresses this problem may need to address, including what types of limitations the system imposes. These will be the initial thinking around criteria and constraints for the design solution, which students will come back to later. Come together as a class and ask students to share some of their thinking, using this as an opportunity to consider the particular challenge of moving materials up a mountain.
Mountain system: forces determining motion up the side of a mountain
Draw a picture of a mountain on the board, with a picture (e.g., a box) representing cargo to be delivered to mountain villages at the bottom. As a class, ask students what information they may need to know to figure out how to get the cargo to the villagers. Some student responses may be:
- How far up the mountain the villages are located
- How much cargo will need to be delivered
Ask students to consider what forces are contributing to/limiting the movement of the cargo. Have students draw a diagram of the forces involved (note: depending on students familiarity with different types of forces, these diagrams may have specific forces or descriptions of the types of forces needed- focus on conceptual understanding, not vocabulary), and ask them to think about what the major challenge of moving cargo up a mountain, in terms of forces, is. Use this conversation to help students understand that gravity is pulling the cargo downward, and there needs to be an applied force that is countering the impact of gravity (note: at this level, students will likely only be thinking about vertical forces, not horizontal forces involved in moving cargo up an incline- this is fine for this lesson). Ask students to update their force diagrams of the mountain-cargo system, based on their new thinking after this conversation.
Ask students to brainstorm some methods of getting from the bottom of the mountain to the top (or some realistic point where the villages might be located). Encourage students to be creative and record their responses on the board (This initial brainstorm serves as a way to assess student thinking and prior knowledge.) Student responses will likely include a range of ideas, from physically carrying materials up the mountain to more automated ideas. Tell students that they will need to identify and justify what type (manual or automated) of solution will work best to carry relief supplies to villagers in the mountains. Ask students to return to their force diagrams of the mountain, and obtain information from reliable sources as they consider:
- What types of resources would need to be carried?
- What is the relative mass of the cargo likely to be?
- How will the mass of the cargo impact the force needed to move the cargo to its destination?
- How well would humans (or other organisms) be able to be the primary force moving the cargo?
- How well would an automated mechanism be able to be the primary force moving the cargo? (note: you may want to be specific about what these types of mechanisms might be, such as a ski lift, depending on student responses to the initial prompt)
- How fast will each mechanism get the cargo to the villagers who need them?
- What are the costs and limitations of each type of cargo-moving mechanism?
Ask students to construct an argument, based on evidence from their force diagrams and the information they have gathered, for which type of mechanism for transporting the cargo to the mountain villages would be a better choice. Make sure students work through:
- Possible claims
- Evidence, including sufficiency and necessity
- Alternative interpretations of evidence, and why the evidence collectively supports the students’ claim over other possible claims
- Reasoning
Have some students share their arguments, and use this discussion to come to a class consensus that the mechanical ways of moving cargo will likely be a better way to get materials to the mountain villagers.
Continue this discussion by presenting students with an image or video of a ski lift. Ask students to use their prior knowledge and/or the image to think about how a ski lift works. Ask students to independently create an annotated drawing of how they think the lift works. (You can use the annotated drawings as an assessment tool to identify student thinking prior to designing the solution.) Encourage students to use their research for their argument to supplement their thinking.
After students have had time to work, ask students to get into small groups and share their annotated drawings with their group members. Ask students to identify:
- Common features among all of the annotated drawings
- Differences between the drawings, and why they are different
- Important features for the design, and why those features might contribute to the function of the design
Tell students that today they will be designing a model of a chair lift that could be used to help move supplies and cargo to the mountain villages. Instead of moving real supplies, they will be moving a Ping-Pong ball that will represent the supplies to be moved. The “mountain” is 2 ft. high and each lift must be able to transport the ball "up the mountain" and "down the mountain" without the ball dropping out of the chair they develop to hold the Ping-Pong ball. Ask students to consider this model system, and identify and describe how it is similar to the real situation, and what the limitations of the model system are, which will impact how they think about their designs.
Before students begin designing, present students with the materials that they can use. Then, work as a class to decide on criteria and constraints, as well as a system for testing and evaluating the success of each lift. Remind students that criteria and constraints define the necessary features of the system to think about when designing a solution to the problem, and knowing the evaluation plan influences how engineers design and build products and systems. Have students refer back to the information they have gathered throughout the lesson, and first determine the criteria and constraints they would define for the real-life system, and then think about how these might translate to the model system, including a rationale for their decisions. Have students work independently initially, share with their design groups, and then be ready to share with the class.
As a class, determine the key criteria and constraints for the design, and how they relate to both the model system as well as the real life scenario. Once the design criteria and constraints have been identified, have students think about how these will translate to the evaluation system.
Sample Evaluation Criteria and Constraints
- After placing the ball in the chair, no hands can touch the ball, because an automated cargo system may not be manned, and would have to be self-restrained.
- You cannot tape the ball to the chair, because this would be difficult to do in real life
- The ball must make it up to 2ft. before beginning its descent, because this is the proxy for reaching the villagers.
- The ball must make it up and down again within two minutes in order for the test run to be considered successful, because timing of the run is critical when delivering relief supplies.
- All groups will get at least 3 trials, because this is a design and testing situation, and we need to see if a solution works consistently or inconsistently.
Now, instruct students to work with their design team to create a new, detailed drawing of what their model chair lift will look like and how it will function. As students work on their drawing, circulate and ask questions about their design decisions, including why certain materials/shapes/structures are being used for specific purposes. When students have finished their drawing, ask the class to create a list of the components of the ski lift system they designed. Have the class share their lists. Were there any differences, i.e., did any groups have system components that the other groups did not have? If so, are these components necessary to the functioning of the system? Were they necessary to include in the design? If not necessary, what added benefit do they provide? Give students an opportunity to revise their drawing based on this conversation if they wish.
Then ask student to brainstorm and add the forces they think are important to the functioning of the system into their drawing, thinking back to their original thinking about the real-life mountain system. If necessary encourage them to think about different parts of the system (the chair, the Ping-Pong ball, the mechanism for moving the chair) separately. Ask them if identifying these forces makes them think about their designs differently? If so, how? Ask them to consider what other forces and factors they might need to consider when designing a lift for carrying cargo to the mountain village that the students do not need to consider for their design (some examples might include wind, rain, soil type, etc.). Depending on students’ familiarity with models, you can ask them if the drawing they created is a model and why. You can also ask them to identify the limitations of their model.
Students should submit their final design to you before building so that you have the opportunity to identify potential issues they might encounter and to assess their thinking about their designs and understanding of forces. This will also help with materials management.
Investigation 2: Designing and Testing
Materials
- For each group: Ping-Pong ball, string, floral wire, pipe cleaners, bendable aluminum wire, straws, paper towel tubes, paper clips, tape, balloons, glue, string, foil, plastic wrap, pulley, other items available in the classroom.
Instructional Sequence
Give the teams time to build. The amount of time you can dedicate to this project is up to you. Keep students on task by setting interim deadlines.
- Design Review: Midway through the building phase, have groups give brief presentations to the class discussing their designs. Allow time for questions from their peers.
After groups are done building, test each ski lift according the agreed upon evaluation plan. As each group tests, all other groups should be taking note of the design and success of their peers’ lifts. Encourage students to think about the function that each materials plays in the lift system. Do certain materials lend themselves to certain uses? (As an additional accommodation, you can create a worksheet that will support students in recording their observations during testing.)
Once all groups have tested, ask each student to work independently to write down three features or materials that seemed to contribute to the success of successful designs as well as why they think this, and features that didn’t contribute to the successful design (or may have made the design unsuccessful) and why they think that is. Encourage students to think about this in terms of structure and function, cause and effect, and forces acting on the structures (Use these responses as an assessment tool.)
Investigation 3: Redesigning and Testing
Materials
- For each group: Ping-Pong ball, string, floral wire, pipe cleaners, bendable aluminum wire, straws, paper towel tubes, paper clips, tape, balloons, glue, string, foil, plastic wrap, pulley, other items available in the classroom.
Instructional Sequence
Instruct students to return to their design groups. Ask students to report on what they saw in their initial designs- what worked? What didn’t work? What might make their designs better? Tell students that iteration, the process of refining and retesting a design, is an integral part of the engineering process. Inform students that they will now have the opportunity to redesign and retest their lifts using the results of investigation 2 to inform their designs.
If needed, remind students about the criteria and constraints of the challenge.
Use the same process as Investigation 2 to have students refine and retest their lifts. In addition to testing the lift, each group should explain what changes they made to their design as well explain why they made those changes.
After all student groups have tested, once again ask students what features seemed to lead to successful or unsuccessful lifts.
Investigation 4: Changing the Mass
Materials
- For each group: golf ball, container with water, paper towel tube, Styrofoam tray, paper towels
- Observation Directions Worksheet
Instructional Sequence
Have students return to their design group. Ask students to reflect on their designs relative to the real-life problem- what were some of the limitations in their model of the solution and system? Record student ideas, making sure they think about the relative mass (you can remind them to think about their findings from the information they gathered). Ask students whether the mass of the supplies needed to get to the villagers would always be constant? How could they model changes in mass, particularly heavier masses, here? Allow students to share their ideas, and then inform students that instead of carrying a Ping-Pong ball, they must now ensure that their lift can carry a golf ball up and back down a 2 ft. “mountain”. The evaluation criteria should remain the same.
Ask students “What are some similarities and differences in the force needed to move a Ping-Pong ball and a golf ball?”
Tell students that they will now work with their design teams to investigate the differences further. Pass out the Observation Directions Worksheet, and instruct students to follow the instructions. (As an accommodation for some students, you may wish to go through the activities and worksheets as a class. Additionally, you can add visuals to the worksheet.)
After students have had time to make and record observations, come back together as a class, and ask groups to share out their observations. Help students focus in on the idea that since the golf ball has greater mass, more force was needed to cause the same change in motion than was required to move the Ping-Pong ball.
Investigation 5: Redesign and Presentations
Materials
- For each group: string, floral wire, pipe cleaners, bendable aluminum wire, straws, paper towel tubes, paper clips, tape, balloons, glue, string, foil, plastic wrap, pulley, other items available in the classroom.
- Presentation Rubric
Instructional Sequence
Inform students that they will now work with their design groups to use the data they just gathered to inform the redesign of their lift to accommodate a golf ball.
Before groups begin designing, ask each student to independently write a response to the following prompt: “What changes do you need to make to your design to accommodate the heavier mass and why?” (Use this written response as an assessment tool. You can also use this as an opportunity for individual check ins with students who might need additional support.)
Have students return to their groups. Once again, have students submit a drawing prior to building, and then allow students time to build. After all groups have built their designs, students should follow the same protocol to test the lifts and record results.
After all students have tested, tell students that they will work with their design groups to prepare for short presentations, which will include:
- Relevant information about the real-life problem and criteria and constraints (including information about the impact of natural hazards and forces)
- How this was translated into a model of the system
- The initial design and redesign efforts, including a discussion of forces and how forces were observed and recorded
- Modifications made due to mass changes- what was the relative force needed?
- The relationships between structure and function of the models
- How this entire process relates to the real-life problem, including an argument to answer to question: “Would your model chair lift be a good model for engineers to use to develop a supply system for mountain villages in Nepal following the recent earthquake?”, including a discussion of structure and function and system models (note: if students need extra support in constructing arguments, remind them of all the sources of evidence used in this lesson, as well as the guidelines for argument included earlier)
Review the Presentation Rubric as a whole class before students break into their groups.
Possible Extensions: For students that have met the criteria or have a high interest, change the standards for success criteria and make them more challenging (e.g., shorten the time needed to get the objects up and down the incline, increase the incline, remove some of the materials that students can use). Additionally, you can have students use the data they have collected to make predictions about the changes that would need to be made to accommodate balls of different masses.
