Middle School Engineering Challenges: Discipline Specific by Grade Levels

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Grade Six Discipline Specific Course Model: Earth and Space Science

Engineering Connection: Solar Array Design Chapter 6,   p. 599

This concept has important engineering applications for solar energy California hosts several of the world’s largest arrays of solar panels. When people place solar panels on their roofs, the angle of the panels is usually fixed by the angle of the roof.   To maximize efficiency at large solar power arrays, the motors constantly turn the panels so that they face the Sun at an angle as close to 90 degrees as possible to get the maximum energy output.  Students can experience this effect in a classroom with a small solar panel hooked up to an electric motor.  As they rotate the solar panel to change the angle of sunlight, the energy output changes (CCC-7), so that the motor turns at a different speed (New York State Energy Research and Development Authority 2015).    Students could engage in an engineering challenge to design a rotating base for solar panels that has the necessary range of movement (both tilting and swiveling) and uses low-cost materials. (MS-ETS1-1, MS-ETS1-2)

Engineering Connection: Solutions To Pollution Moved By The Water Cycle
Chapter 6,   p. 617

Moving water often carries pollutants along with it (EP&C IV), but understanding the water cycle allows people to design measures to reduce or stop the flow of pollution. One possible engineering challenge for students, is to deal with the flow of water and pollutants in urban areas. As water runs along road surfaces, it picks up oil, grit, and other pollutants that flow into storm drains and out into local waterways.   During heavy rainstorms, those waterways can get overloaded and flood.  Allowing a greater fraction of water to infiltrate into the ground can solve two problems:  

First it reduces the amount of water on the surface that causes flooding and, second, the soil filters out many harmful contaminants before they enter groundwater or surface water.   Students can be given the challenge of designing a system that diverts waters into the ground and provides the maximum filtration of that water (for example, see Engineering is Everywhere, Don’t Runoff: Engineering An Urban Landscape accessed at https://www cde ca gov/ci/sc/cf/ch6 asp#link24). Students will have to define specific criteria to measure their success (MS-ETS1-1), brainstorm and compare different possibilities (MS-ETS1-2), test those possibilities (MS-ETS1-3), and make iterative improvements. (MS-ETS1-4)

Engineering Connection: Cement and Sedimentary Rocks
Chapter 6,  p. 623

Students may not realize it, but they are already familiar with sedimentary rocks because most materials in the built environment such as roads, sidewalks, bricks, and concrete are essentially artificial sedimentary rocks with small pieces of rock material cemented together.  The average American is responsible for the use of nearly 9 tons of crushed rock material every year of their life (USGS 1999b).   These artificial materials are carefully engineered to have sufficient strength at the lowest cost.  Students can obtain information (SEP-8) about where rock aggregate comes from in their community (it is very heavy and expensive to transport and usually quarried as locally as possible).

The process of cementation of natural sedimentary rocks usually occurs slowly underground as mineral-rich water flows through pore spaces between grains, but it can be sped up by adding concentrated cement minerals and water in a concrete truck. To develop a model (SEP-2) of how sedimentary rocks form (such as figure 6.14; MS-ESS2-1), students can engage in an engineering challenge to create the most durable concrete from plaster of paris and rock pieces of different sizes and shapes (sand, smooth pebbles, angular pebbles, etc.).  (A short snippet for this idea is accessed at https://www cde ca gov/ci/sc/cf/ch6 asp#link25 ). They decide the ideal proportions (CCC-3) to mix the materials in small paper cup.   After letting their “concrete” dry, they remove the paper cup and see whose material is strongest by piling on different amounts of weight or dropping it from different heights (MS-ETS1-2).  This process helps motivate the rest of the instructional segment as it provides students a physical model for the steps of sedimentary rock formation as well as introducing them to the idea that rocks are broken down through the process of erosion.

Engineering Connection: Earthquake Early-Warning System
Chapter 6, p. 640

The only part of the process that is not yet predictable is the exact timing of the earthquakes . While scientists have investigated (SEP-3) a wide range of monitoring strategies, it appears that many earthquakes occur without any perceivable trigger.   That means that the soonest we can know about earthquakes is the moment that they first start.   Earthquake waves do take time to travel through the Earth, so there is one more way that understanding earthquakes can help us mitigate their effects.   The moment a seismic recording station detects shaking, it can send a signal at the speed of light to a central processing center that can issue a warning of the impending earthquake.   Such warnings can be distributed to schools, businesses, and individuals via the Internet, mobile phones, and other broadcast systems, providing them warning of a few seconds to a minute.  Such systems have been in successful operation in Japan and Mexico City, and a prototype is being tested in California.

After investigating patterns (CCC-1) of earthquake occurrence in their region, students can make decisions about where to place seismic recording devices to design their own earthquake early-warning network that provides the maximum advance warning (MS- ESS3-2) (d’Alessio and Horey 2013).  Using an online simulator (see Earthquake Early-Warning Simulator at https://www cde ca gov/ci/sc/cf/ch6 asp#link36), students test their network’s performance in sample earthquakes, compare network designs with their peers (MS-ETS1-2) and iteratively improve them. (MS-ETS1-3)

           Grade Seven Discipline Specific Course Model: Life Science

Engineering Connection: Engineer a Bird Beak
Chapter 6 , p. 690

In elementary school, students constructed arguments about internal and external structures of organisms that help them survive. (4-LS1-1)  In this activity, they engineer structures and use their own designs to make inferences about how the internal and external structures of an animal connect and interact.   Different animals eat different types of food, and their bodies must have the correct structures (CCC-6) to enable them to eat that food effectively.  Birds in particular have large variation in their beak shapes based upon their food source.   Students can design a “beak” from a fixed set of materials that will allow them to “eat” as much “food” as possible (for example, see Curiosity Machine, Engineer a Bird Beak at https://www cde ca gov/ci/sc/cf/ch6 asp#link46).

They begin by defining the problem and establishing the criteria they will use to measure success. (MS-ETS1-1, MS-ETS1-2) Will they compare the amount of food in one bite or the amount of food obtained in a set amount of time? Which of these criteria is probably a better approximation of what helps birds survive in nature? Are there any specific challenges that the particular type of food presents (powders, foods encased in hard shells, and foods that crumble easily all require different solutions)? Are there any obvious disadvantages to bigger or smaller beaks? (To represent the fact that bigger organisms require more energy (CCC-5) to survive, the activity can be set up so that the number of points a team receives depends on the ratio of food mass eaten to the beak mass).  They discuss the process of iterative improvement that they used and then compare and contrast it to evolution by natural selection, which occurs over many generations.

In their own engineering design, students might notice that certain modifications they made allowed them to eat food faster, allowing them to collect more food each day— a serious advantage for survival Scientists have found that seed-eating birds that have the strongest bite force can eat the fastest.    What aspects of a bird’s structure allow it to bite more forcefully? Students analyze measurements of different physical characteristics of different species of finches from the Galapagos and compare them to the bite strength scientists measured in laboratories.  Different students plot different variables to see if they can identify variables that correlate well with bite strength (Herrel et al 2005). They find that the length of the beak doesn’t matter, but the size of the head does, probably because larger heads can support larger muscles (figure 6 29). They can experiment with different modifications to their bird beaks that mimic these size differences and relate them to levers and forces.

Engineering Connection: Engineer a Bird Beak Figure 6.29. Analysis of Different Physical Characteristics of Finches

Source: Herrel et al 2005; charts by M d’Alessio Long description of Figure 6.29

Engineering Connection: Using Technology to Enhance an Ecosystem  p. 697

Some human activities have negative impacts on ecosystems, but some technologies enhance ecosystem productivity by providing valuable ecosystem services such as the purification of water, reduction of soil erosion, or recycling of nutrients. Students investigate (SEP-3) competing technologies or various design alternatives of a given technology to see which is most beneficial to the ecosystem (MS-LS2-5).

One classroom-friendly possibility is to explore different designs of compost systems (CCC-4) to optimize nutrient recycling. Students can learn more about the valuable role of decomposers by performing a service for their school by collaborating with the campus cafeteria and garden or facilities staff.  Students can test competing compost systems (CCC-4) to see which will produce nutrient-rich organic fertilizer the fastest. Their designs might explore different amounts of air circulation, mixing of compost material, ambient temperatures, and additions of water or other materials (such as coffee grounds), all of which might affect the rate of biochemical reactions that decompose food waste.

Grade Eight Discipline Specific Course Model: Physical Science

Engineering Connection: Reducing the Impact of Collisions
Chapter 6, p. 704

The unit begins with a design challenge in which students use a fixed set of materials to reduce the damage during a collision (MS-PS2-1). The classic egg drop could be used, but many of the solutions to that problem involve slowing the egg down before the collision (via parachute).  The emphasis for the performance expectation is on applying Newton’s Third Law that objects experience equal and opposite forces during a collision.   A variation in which students attach eggs to model cars and design bumpers to protect the eggs, allows for a consistent theme of car crashes throughout the instructional segment and vehicles in general throughout the course.  Students will need to identify the constraints that affect their design as wellas the criteria for measuring success (MS-ETS1-1).   Such a design challenge could be placed at the end of IS1 as a culmination in which students apply what they have learned from investigations (SEP-3) throughout the instructional segment.   However, here the choice is made to explicitly use an engineering task to draw attention to the variables of interest in the problem.   By identifying the common features of successful models (MS-ETS1-3), students can identify the physical processes and variables that govern the process.  Students will then investigate these variables more systematically throughout the rest of the instructional segment.   At the end of IS1, students return to their design challenge and explain (SEP-6) why certain choices they made actually worked (perhaps identifying important structure and function relationships (CCC-6) in their designs) and then use their more detailed models of the system (CCC-4) to refine their design.

Engineering Connection: Reducing the Impact of Collisions (con’t.)   p. 709

Students are now ready to return to their design challenge of reducing the impact of a collision (MS-PS2-1).  They should be able to use their models of energy (CCC-5) transfer and kinetic energy to make an argument (SEP-7) about why their original design solution worked.  Two different processes help bumpers reduce damage during collisions: (1) they absorb some of the energy so that less of it gets transferred to kinetic energy in the target object (the absorbed energy gets converted to heat); and (2) they make the collision last longer, so that the transfer of energy occurs over a longer time interval (since speed changes at a slower rate, Newton’s laws tell us that a smaller force is exerted on the cars).  Students can create energy source/receiver diagrams that are more sophisticated than figure 6.31 to describe the energy flow during a collision that includes a bumper.  These diagrams should help students describe how Newton’s Third Law helps them design their solution, and begin to ask questions (SEP-1) about where the energy actually goes during the interaction. They should also be able to propose improvements to their bumper (MS-ETS1-2, MS-ETS1-4) using the results of a more sophisticated testing regime and their enhanced understanding of the physical processes .

Engineering Connection:   8th Grade Physical

Engineering Challenge: Design a Vehicle Radiator
Chapter 6, p.740

Many systems (CCC-4) from human bodies to spacecraft operate best when they are neither too hot nor too cold.  Living organisms have evolved so that they have mechanisms to avoid overheating (dogs pant, people sweat, rabbits have large ears, etc. ) or becoming too cold (birds have inner down feathers, mammals have layers of fur, penguins huddle in groups, etc. ). Many of these adaptations illustrate how the heat transfer function (CCC-6) is supported by the specific shape or structure (CCC-6) of the organism.   Thermal regulation is also important in many different technologies. Obvious examples include keeping the inside of refrigerators cool and the inside of ovens warm, but engineers also include thermal regulation in the designs of a variety of technology.  Computer chips that are present in just about every electronic object become damaged when they overheat, so almost all of these everyday objects also include design elements to keep them cool.  Students engage in a design challenge in which they plan, build, and improve a system (CCC-4) to maximize or minimize thermal energy (CCC-5) transfer (MS-PS3-3).

Ideas for the challenge include designing well-insulated homes (Concord Consortium, Build and Test a Model Solar House at https://www cde ca gov/ci/sc/cf/ch6 asp#link60), a beverage or food container (NASA, Design Challenge: How to keep gelatin from melting at https://www cde ca gov/ci/ sc/cf/ch6 asp#link61), a solar oven (Teach Engineering, Hands-on Activity: Cooking with the Sun at https://www cde ca gov/ci/sc/cf/ch6 asp#link62), or even a cooling system for a nuclear powered submarine (Lisa Allen, Historic Ship Nautilus: Submarine Heat Exchange Lesson Plan at https://www cde ca gov/ci/sc/cf/ch6 asp#link63).

This design challenge could also be integrated into the course theme of vehicles by having students design an effective radiator for a car. Their design could take advantage of liquids with different heat capacities flowing through tubes and/or fin-shaped metal heat exchangers, just like the radiators in the cars and buses that might take them to and from school. Students can consider the environmental impact of different materials as one of the many factors constraining their design (MS-ETS1-1).  Because the performance of thermal regulation systems is easy to measure with a thermometer, students plan ( SEP-3)pa rigorous testing process (MS-ETS1-4), analyze the data (SEP-4) from the tests (MS-ETS1-3), and evaluate (SEP-8) different potential solutions (MS- ETS1-2) to iteratively improve their final design. Heat flow is also easily simulated on a computer using software that is available for free. (Concord Consortium, Energy2D)

Engineering Connection: Engineering Challenge: Design a Vehicle Radiator con’t.   p. 741

Interactive Heat Transfer Simulations for Everyone at https://www cde ca gov/ci/sc/cf/ ch6 asp#link64), allowing students to perform some of their planning and initial testing and revision in a simulator before actually building any physical objects. During the design process, students will likely need to become familiar with different mechanisms of heat transport (conduction, convection/advection, and radiation).

While these processes are not explicitly mentioned in the performance expectations for grade eight, students should be applying scientific principles to guide their design; for example, different methods of heat flow require different design strategies to exploit or minimize overall energy (CCC-5) transfer.   

Such information could have been introduced during the investigations (SEP-3) of MS-PS3-4, but the emphasis there was on the quantity (CCC-3) of overall energy transfer and different mechanisms were not essential.  The distinction becomes more important for this design challenge because effective insulation designs often need to reduce all three mechanisms and effective heat exchange designs typically exploit them all.   Students should already have applied models of convection to understanding energy (CCC-5) in Earth’s atmosphere and interior during grade six. (MS-ESS2-1 and MS-ESS2-6)    

Students can now relate their macroscopic understanding of heat transport processes to their models of the movement of individual particles.  Conduction involves the transfer of energy directly by collision between particles.   Energy moves in convection when particles with large amounts of thermal energy move to a different location and take their energy along with them.

Hot particles can also radiate energy as electromagnetic waves, which can be absorbed by other particles during the energy transport process called radiation.   Students finish the activity by creating a product information sheet in which they argue (SEP-7) that people should buy their product.   They will communicate (SEP-8) the features of their product that allow it to perform better than their imaginary competitors as well as evidence (SEP-7) from their investigations (SEP-3) and testing showing that it actually does.

Engineering Connection:   8th  Physical Science

Designing a Hand Warmer Powered by Chemical Reactions
Chapter 6   p. 747

Students now imagine that they will travel to a very cold place to explore and play and that they will want a way to keep their hands warm for as long as possible. Their goal is to analyze data (SEP-4) from the previous experiment to help design a hand-warming pad powered by chemical reactions. (MS-PS1-6)   Students will need to define the criteria (SEP-1)for judging hand warmer performance (MS- ETS1-1).    Is it best to have the hand warmer reach its peak temperature quickly and cool back down quickly, or to warm slowly to a lower peak temperature?

The engineering challenge works best when the whole class records its findings from the mixtures with two powders and a liquid in a collaborative spreadsheet so that a large number of unique combinations can be tested. Students should discover patterns (CCC-1) in the class observations to identify which two materials consistently react before they select their materials and begin to test them. They then perform iterative tests to determine the relative concentration of the two ingredients that lead to optimal hand warmer performance. (MS-ETS1-2, MS-ETS1-4).  By communicating (SEP-8) their findings to the class, teams with different solutions can compare the relative performance of their hand warmers to decide the relative merits of each one. (MS-ETS1-3)