Student Name:_____________ Class: ______

Solar Cooker

Engineering ChallengeStudent Materials

D R A F T 1

Solar Cooker Engineering ChallengeStudent Materials

Most people in the United States use an electric stove or a natural gas stove to cook their food. This is not the case in much of the world. Approximately 50% of the people on Earth cook using fire from burning wood. However, due to overuse, wood is becoming a scarce commodity in many countries. In addition, burning wood is a major source of air pollution.

One alternative to cooking with wood is using solar cookers. These devices use energy from the sun to cook food without producing any pollution. Since the invention of the first solar cooker in 1767 by French-Swiss scientist Horace de Saussure, many different types of solar cookers have been created. There are three typical solar cooker designs, heat trap boxes, parabolic, and panel cookers. While there are many designs for solar cookers, a simple solar cooker can be made from everyday materials. Watch the video “Yes We Do Solar Cook” provided by your teacher which was filmed at the July 2014 Solar Cooking Festival to see some of the different types of solar cookers being used today.

Your TaskYou and your group will design and build your own solar cooker using the materials provided to you by your teacher. Your challenge is to heat up 50 grams of water to the highest temperature possible in the time allotted to you by your teacher. Your solar cooker cannot be larger than 60cm x 60 cm x 60 cm. Your design should be based upon solid scientific knowledge collected from research. You will be expected to do the following:

Research solar cookers Create drawings of your prototype Build the prototype Test the prototype Analyze the data collected Make a change to the prototype Retest the prototype Analyze the data collected Draw conclusion on the effectiveness of the prototype Identify issues with your prototype Provide one addition modification that could be made

As part of the engineering process, you must document the steps that you went through in order to create your final prototype in the form of a design journal. The requirements for the design journal are found on the following page. To help you start your research, please refer to the article found on pages 8-11 called “Principles of Solar Box Cooking Design.” Identification of the engineering challenge: Identify in detail the engineering challenge you are faced with. You should clearly identify the given constraint and specifications you have been held to.

Research: Explain how solar cookers serve as an example of energy transformations along with the specific energy transformations that are occurring in a solar cooker. The benefits of using solar cookers over traditional means of cooking should be explained. The parts of a solar cooker should be identified as well as how they function to create a working solar cooker. Areas of solar cookers that lead to a loss of energy to the surroundings should be identified.

D R A F T 2

Initial Engineering Drawing: Construct multiview (top, front, side) drawings of your prototype solar cooker. The drawing should be labeled to include materials used as well as the dimensions of the prototype in metric units. Your teacher may ask you to create your drawing to scale.

Rationale for Design: You will need to justify the engineering decisions that were made when you designed your solar cooker. For example if you decided to make your solar cooker out of foam board instead of cardboard, the scientific reasoning for that decision needs to be explained. This can be done in a chart as shown below:

Engineering Decision Scientific basis for your decisions

Prototype: After the prototype is created, the teacher should be provided an opportunity to assess the prototype for grading purposes. If the journal is digitally created, photographs of the prototype should be provided.

Test Results: Construct a data table displaying how the temperature of the water inside the solar cooker changed over time. Construct an x-y scatter graph from the data, draw a line of best fit and determine the equation for the line using graph paper or an appropriate graphing program such as Excel.

Revised Engineering Drawing: Create revised multiview (top, front, side) drawings of your solar cooker prototype. The drawing should be labeled to include material used as well as the dimensions of the prototype in metric units.Rationale for Revised Design: Justify the engineering change that was made to your prototype based upon evidence collected during the testing of your own prototype as well as data from other group’s test.

Test Results for Revised Prototype: Construct a data table displaying how the temperature of the water inside the solar cooker changed over time. Construct an x-y scatter graph from the data, draw a line of best fit and determine the equation for the line using graph paper or an appropriate graphing program such as Excel.

Final Evaluation of Solar Cooker: Evaluate your solar cooker to determine if the changes made to the prototype were effective based upon evidence collected. At least two limitations of your solar cooker prototype need to be identified as well as one further change that could be made to the solar cooker in order to improve its performance.

The rubric for grading your design journal can be found on the following page.

D R A F T 3

Rubric for the Evaluation of the Solar Cooker Engineering Challenge

3 2 1 01. Clarify design challenge’s specs & constraints(Practice 1,HS-ES1-1)

Explained the design challenge in detail and accurately described the given constraints and specifications.

Explained the design challenge in a few sentences and described two constraints and/or specifications.

Briefly explained the design challenge and described one constraint and/or specification.

Did not explain the design challenge and its criteria.

2. Research(Practice 5, 8,)

Described relevant information on: the benefits of

using a solar cooker over traditional cooking methods

the energy transformations that occur in solar cookers

Information presented in a clear and coherent way. Information should come from a minimum of 3 credible sources.

Described information gathered through research in a clear way, from less than three credible sources.

Described partial information gathered through research from only one credible source.

Did not describe results from research.

3. Generate a solar cooker design

(Practice 2, HS-ETS1-2, HS-G-MG.3*)

The multiview (front, side, top) drawings of the prototype are created with detail.

The multiview drawings of the prototype are created but lack detail.

The multiview drawings of the prototype are partially completed.

Drawings are not completed.

4. Select & justify solar cooker design

(Practice 2, 6, 8, HS-ETS1-2)

Used data/evidence from the research to justify the initial design.

Used some data/evidence from the research to justify the initial design.

Used limited date/evidence from the research to justify the initial design.

No explanation or justification of the initial design was provided.

5. Build and document the prototype

(Practice 3, HS-ETS1-2)

The final prototype was neat, organized, and matched the multiview drawings.

The final prototype was acceptable and matched the multiview drawings.

The final prototype was poorly built and loosely resembled the multiview drawings.

The final prototype was missing or did not resemble the multiview drawings.

D R A F T 4

6. Test and evaluate the prototype

(Practice 4,5,8, HS-S-ID.6, HS-S-ID.6c)

A data table, X-Y scatter graph, line of best fit, and linear equation were correctly generated illustrating how the temperature changes over time for both the initial and revised prototypes.

A data table, X-Y scatter graph, line of best fit and linear equation were generated illustrating how the temperature changes over time for both the initial and revised prototypes with minor errors.

A data table, X-Y scatter graph, line of best fit and equation were generated illustrating how the temperature changes over time for both the initial and revised prototypes with major errors or omissions.

The data collected was not displayed in any format.

7. Revise the solar cooker

(Practice 2, 3, 4, 6, 7, HS-ETS1-2)

One change to the prototype was made in an attempt to improve performance. The change to the prototype was based upon evidence collected. Revisions to the multiview drawings occurred.

One change to the prototype was made in an attempt to improve performance. The change to the prototype was not justified well. Revisions to the multiview drawings were not detailed.

One change to the prototype was made in an attempt to improve performance. The change to the prototype was not justified. Revisions to the multiview drawings were poorly done.

No change was made to the solar cooker prototype.

8. Final evaluation of solar cooker.

(Practice 4, 6, 8, HS-ETS1-2)

Students correctly identified how the change made to the prototype affected the performance of the solar cooker with strong evidence from data.

Students correctly identified how the change made to the prototype affected the performance of the solar cooker with some evidence from data.

Student identified how the change made to the prototype affected the performance of the solar cooker with no supporting evidence.

Student did not correctly identify how the change made to the prototype affected the performance of the solar cooker and provided no supporting evidence.

9. Further engineering changes

(Practice 2, 6, 8, HS-ETS1-2)

Student identified two limitations to their design and one further improvement that could be made.

Student identified one limitation to their design and one further improvement that could be made.

Student identified one limitation to their design and failed to identify any one further improvement.

Student did not identify any limitations or identify one further improvement.

For students with higher mathematical ability, multiview drawings can be drawn to scale

D R A F T 5

Scoring Summary for the Design Portfolio

Student ID#: _________________________ Teacher name: ____________________________School: _____________________________ District: _________________________________Date: _______________________________

Assessment ElementsAssessment Points

Points Possible

Reviewed bySelf Teacher

1. Clarify design challenge’s specs & constraints 3

2. Research 3

3. Generate a solar cooker design 3

4. Select & justify solar cooker design 3

5. Build and document the prototype 3

6. Test and evaluate the prototype 3

7. Revise the solar cooker 3

8. Final evaluation of solar cooker 3

9. Further engineering changes 3

Total points 27

Overall Score (A=20-24; B=14-19; C=8-13; D=5-8; F=0-4)

D R A F T 6

Principles of Solar Box Cooker DesignBy Mark Aalfs, Solar Cookers International

The purpose of this paper is to summarize the basic principles that are used in the design of solar box cookers.People use solar cookers primarily to cook food and pasteurize water, although additional uses are continually being developed. Numerous factors including access to materials, availability of traditional cooking fuels, climate, food preferences, cultural factors, and technical capabilities, affect people's approach to solar cooking.With an understanding of basic principles of solar energy and access to simple materials such as cardboard, aluminum foil, and glass, one can build an effective solar cooking device. This paper outlines the basic principles of solar box cooker design and identifies a broad range of potentially useful construction materials.

These principles are presented in general terms so that they are applicable to a wide variety of design problems. Whether the need is to cook food, pasteurize water, or dry fish or grain; the basic principles of solar, heat transfer, and materials apply. We look forward to the application of a wide variety of materials and techniques as people make direct use of the sun's energy.

HEAT PRINCIPLESThe basic purpose of a solar box cooker is to heat things up - cook food, purify water, and sterilize instruments - to mention a few.A solar box cooks because the interior of the box is heated by the energy of the sun. Sunlight, both direct and reflected, enters the solar box through the glass or plastic top. It turns to heat energy when it is absorbed by the dark absorber plate and cooking pots. This heat input causes the temperature inside of the solar box cooker to rise until the heat loss of the cooker is equal to the solar heat gain. Temperatures sufficient for cooking food and pasteurizing water are easily achieved.Given two boxes that have the same heat retention capabilities, the one that has more gain, from stronger sunlight or additional sunlight via a reflector, will be hotter inside.Given two boxes that have equal heat gain, the one that has more heat retention capabilities - better insulated walls, bottom, and top - will reach a higher interior temperature.

D R A F T 7

The following heating principles will be considered first: Heat gain Heat loss Heat storage

A. Heat gainGreenhouse effect:  This effect results in the heating of enclosed spaces into which the sun shines through a transparent material such as glass or plastic. Visible light easily passes through the glass and is absorbed and reflected by materials within the enclosed space.

The light energy that is absorbed by dark pots and the dark absorber plate underneath the pots is converted into longer wavelength heat energy and radiates from the interior materials. Most of this radiant energy, because it is of a longer wavelength, cannot pass back out through the glass and is therefore trapped within the enclosed space.The reflected light is either absorbed by other materials within the space or, because it doesn't change wavelength, passes back out through the glass.Critical to solar cooker performance, the heat that is collected by the dark metal absorber plate and pots is conducted through those materials to heat and cook the food.

Glass orientation:  The more directly the glass faces the sun, the greater the solar heat gain. Although the glass is the same size on box 1 and box 2, more sun shines through the glass on box 2 because it faces the sun more directly. Note that box 2 also has more wall area through which to lose heat.

D R A F T 8

Reflectors, additional gain:  Single or multiple reflectors bounce additional sunlight through the glass and into the solar box. This additional input of solar energy results in higher cooker temperatures.

B. Heat lossThe Second Law of Thermodynamics states that heat always travels from hot to cold. Heat within a solar box cooker is lost in three fundamental ways: Conduction, Radiation, and Convection Conduction:The handle of a metal pan on a stove or fire becomes hot through the transfer of heat from the fire through the materials of the pan, to the materials of the handle. In the same way, heat within a solar box is lost when it travels through the molecules of tin foil, glass, cardboard, air, and insulation, to the air outside of the box.

The solar heated absorber plate conducts heat to the bottoms of the pots. To prevent loss of this heat via conduction through the bottom of the cooker, the absorber plate is raised from the bottom using small insulating spacers as in figure 6.Radiation: Things that are warm or hot -- fires, stoves, or pots and food within a solar box cooker -- give off heat waves, or radiate heat to their surroundings. These heat waves are radiated from warm objects through air or space. Most of the radiant heat given off by the warm pots within a solar box is reflected from the foil and glass back to the pots and bottom tray. Although the transparent glazings do trap most of the radiant heat, some does escape directly through the glazing. Glass traps radiant heat better than most plastics.

D R A F T 9

Convection: Molecules of air move in and out of the box through cracks. They convect. Heated air molecules within a solar box escape, primarily through the cracks around the top lid, a side "oven door" opening, or construction imperfections. Cooler air from outside the box also enters through these openings.

C. Heat storage:As the density and weight of the materials within the insulated shell of a solar box cooker increase, the capacity of the box to hold heat increases. The interior of a box including heavy materials such as rocks, bricks, heavy pans, water, or heavy foods will take longer to heat up because of this additional heat storage capacity. The

incoming energy is stored as heat in these heavy materials, slowing down the heating of the air in the box.These dense materials, charged with heat, will radiate that heat within the box, keeping it warm for a longer period at the day's end.

D R A F T 10

Grades 9-10Curriculum-Embedded Performance Task

Solar Cooker

Engineering ChallengeTeacher Materials

D R A F T 11

Grade/course High School Physical ScienceTask Name Solar Cooker Engineering Challenge

Task Summary In this task students utilize engineering design principles along with knowledge of energy transformations and heat to design a solar cooker that can raise the temperature of water. Students will acquire prerequisite knowledge of how solar cookers are currently designed before designing and refining their own. Students will be challenged to draw a schematic of their solar cooker, build the solar cooker, test their solar cooker, critique other students’ designs, collect data on their solar cooker, then improve their design. Throughout the engineering process, students will keep a design journal that will document the learning that occurred along the way. The design journal will be used to assess their knowledge of the standards listed in the document.

Prerequisite Standards Next Generation Science Standards Disciplinary Core Ideas

PS3.A: Definitions of Energy Energy is a quantitative property of a system that depends on the

motion and interactions of matter and radiation within that system. That there is a single quantity called energy is due to the fact that a system’s total energy is conserved, even as, within the system, energy is continually transferred from one object to another and between its various possible forms. (HS-PS3-1), (HS-PS3-2)

At the macroscopic scale, energy manifests itself in multiple ways, such as in motion, sound, light, and thermal energy. (HS-PS3-2)(HS-PS3-3)

These relationships are better understood at the microscopic scale, at which all of the different manifestations of energy can be modeled as a combination of energy associated with the motion of particles and energy associated with the configuration (relative position of the particles). In some cases the relative position energy can be thought of as stored in fields (which mediate interactions between particles). This last concept includes radiation, a phenomenon in which energy stored in fields moves across space. (HS-PS3-2)

PS3.B: Conservation of Energy and Energy Transfer Conservation of energy means that the total change of energy in any

system is always equal to the total energy transferred into or out of a system. (HS-PS3-1)

Energy cannot be created or destroyed, but it can be transported from one place to another and transferred between systems. (HS-PS3-1), (HS-PS3-4)

Mathematical expressions, which quantify how the stored energy in a systems depends on its configuration (e.g. relative positions of charged particles, compression of a spring) and how kinetic energy depends on mass and speed, allow the concept of conservation of energy to be used to predict and describe system behavior. (HS-PS3-1)

The availability of energy limits what can occur in any system. (HS-PS3-1)

D R A F T 12

Uncontrolled systems always evolve toward more stable states-that is, toward more uniform energy distribution (e.g. water flows downhill, objects hotter than their surrounding environment cool down). (HS-PS3-4)

PS4.B Electromagnetic Radiation: When light or longer wavelength electromagnetic radiation is

absorbed in matter, it is generally converted into thermal energy (heat). (HS-PS4-4)

ETS1.A Defining and Delimiting Engineering Problems Humanity faces major global challenges today, such as the need for

supplies of clean water and food or for energy sources that minimize pollution, which can be addressed through engineering. These global challenges also may have manifestations in local communities. (HS-ETS1-1)

Common Core State Standards-English Language Arts/LiteracyW.9-10.2Write informative/explanatory texts to examine and convey complex ideas, concepts, and information clearly and accurately through the effective selection, organization, and analysis of content.W.9-10.2aIntroduce a topic; organize complex ideas, concepts, and information to make important connections and distinctions; include formatting (e.g., headings), graphics (e.g., figures, tables), and multimedia when useful to aid comprehension.W.9-10.2dUse precise language and domain-specific vocabulary to manage the complexity of the topic.W.9-10.2eEstablish and maintain a formal style and objective tone while attending to the norms and conventions of the discipline in which they are writing.

Standards Assessed in this performance task.

Next Generation Science Standards Performance Expectations

HSPS3-3 Design, build, and refine a device that works within given constraints to convert one form of energy into another form of energy.

Next Generation Science Standards Science and Engineering Practices:1. Asking questions (for science) and defining problems (for engineering)2. Developing and using models3. Planning and carrying out investigations4. Analyzing and interpreting data5. Using mathematics and computational thinking6. Constructing explanations (for science) and designing solutions (for

engineering)7. Engaging in argument from evidence8. Obtaining, evaluating, and communicating information

D R A F T 13

HS-ETS1-1 Analyze a major global challenge to specify qualitative and quantitative criteria and constraints for solutions that account for societal needs and wants.

HS-ETS1-2 Design a solution to a complex real-world problem by breaking it down into smaller, more manageable problems that can be solved through engineering.

Common Core State Standards-MathHS-G-MG.3 *Apply geometric methods to solve design problems (e.g., designing an object or structure to satisfy physical constraints or minimize cost; working with typographic grid systems based on ratios).HS-S-ID.6Represent data on two quantitative variables on a scatter plot, and describe how the variables are related.HS-S-ID.6cFit a linear function for a scatter plot that suggests a linear association.

* Denotes opportunity for differentiated learning experienceObjectives scored in this

taskThe objectives match the standard noted in the standards assessed section above as well as the following:

Students can identify the benefits for using solar cookers over traditional cooking methods such as utilizing electricity, wood or gas.

Students can identify the energy transformations that occur when a solar cooker is utilized.

Students can identify the components of a typical solar cooker. Students can identify how the components of a solar cooker function

to create heat that can be used to cook food.

Context and Alignment This performance task should be embedded at the end of a unit which covers the topics of PS3.A: Definitions of Energy, PS3.B: Conservation of Energy and Energy Transfer, and PS4.B: Electromagnetic Radiation.

Task Characteristics The task includes 7 sessions, each lasting approximately 45 minutes. An alternative 5 session pacing is also included. The task may be altered in order to meet the constraints of the classroom, schedule, or budget however the engineering components requiring students to define the problem, design a solution, test the solution, and make design changes should be maintained.

Suggested Task Materials This performance task requires: The use of computers or any other source of electronic information

(e.g., smart phones, tablets, etc.) in order for students to gather information.

The use of computer for graphing data or graph paper as an alternative means to create a graph.

Suggested materials for creating solar cookers. Not all of the materials need to be supplied to the students. Teachers should provide some options for students to select from.

D R A F T 14

o Energy Source: Sunlight Heat lamp

o Casing/Structural material: Cardboard Wood Foam board

o Reflective material: Aluminum foil Mirrors Mylar Silver or chrome paint Reflective Tape

o Insulating material: Newspaper Cardboard Cotton Foam

o Transparent Cover/Lid Glass Plexiglass Plastic wrap Shrink wrap Overhead transparencies Sheet protectors Cellophane: clear, yellow, red, blue, green

o Absorption materials: Black paint Black construction paper

o Measurement tools: Thermometer Ruler/Meter Stick

o Vessel to hold 50ml (50g) of water Beaker (various sizes) Paper cup Plastic cup Styrofoam cup Etc

o Additional Supplies Scissors Waxed paper Construction paper Safety goggles Tape (clear and masking) Zip-loc bags Water

D R A F T 15

Suggested Overall Assessment StructureSession Description NGSS Connection

1 Introduction/Research- Students will be introduced to the concept of solar cookers using a 4 minute video found at https://www.youtube.com/watch?v=2_lA4I9__aI. The teacher should prompt students to make a connection between sunlight and electromagnetic radiation and identify the energy transformations that occur when solar cookers are utilized. Students should be able to explain the benefits of using solar cookers as opposed to gas, electrical or wood stoves. Students will be provided with initial article on building solar cookers called Principles of Solar Box Cooker Design and will be allotted time to research solar cooker designs on their own using computers or personal technology.

HSPS3-3Practice 1Practice 5Practice 6Practice 8

2 Model/Construct- Students will engage in discussion/argument with assigned group members in order to determine the most effective design for their solar cooker to meet the engineering problem. Students will create multiview drawings (top, front, side) of their solar cooker design. Engineering decisions need to be justified based upon scientific information collected during the first day. Once their design is completed on paper, students will begin to construct their prototype using the available materials.

HSPS3-3HS-ETS1-3Practice 2

3 Construct/Test/Peer Review-Students will complete the building of their solar cooker prototype. Once construction is finished, the students will test their solar cookers and collect data on how the temperature of the water inside the solar cooker changes over time. While testing is occurring, group members will leave and engage in a peer review of some of the other solar cookers created by their classmates. Students should utilize this time to generate ideas they might implement into future designs as well as provide constructive feedback to other groups on their solar cooker designs.

HSPS3-3Practice 6Practice 7Practice 8

4 Evaluate Data/Modify Design- Students will take the data collected and use it to create an X-Y scatter plot with a line of best fit that can be used to derive a linear equation. Student can use either a graphing program (such as Excel or Logger Pro) or graph paper in order to create the graph of the temperature of the water over time. The graphs of each group’s data will be available to the other groups for evaluation. Once the data has been mathematically calculated, students will use the data they collected on their own solar cooker, the data from other solar cookers, and peer feedback in order to decide upon on modification to their solar cooker that they believe will improve performance. Students should begin to create a new multiview drawings based upon the identified modification.

HSPS3-3Practice 4Practice 5Practice 8

5 Modify Prototype/Test New Design- Students should continue to create a new multiview drawing for their improved prototype. Students will make the modification to the prototype indicated in the multiview drawings.

HSPS3-3Practice 2Practice 3Practice 6

D R A F T 16

Practice 76 Test New Design/Evaluate Results-Students will test the

redesigned prototype and collect data on how the temperature of the water inside the solar cooker changes over time. The data should again be graphed using an X-Y scatter graph and include a line of best fit and an equation that describes the line.

HSPS3-3Practice 3Practice 4Practice 5

7 Completion of Design Journal-Students will be required to complete the design journal that defines the challenge and constraints, illustrates the research performed prior to design, summarizes how energy is transformed in the process of using a solar cooker, the multiview drawings, the results obtained, adjustments made to design and prototype and rationale for adjustments made.

HSPS3-3Practice 4Practice 6Practice 7Practice 8

Suggested Alternative Overall Assessment Structure

Session Description NGSS Connection1 Introduction/Research-

See Session 1 aboveHomework: Students create individual designs at home.

HSPS3-3Practice 1Practice 5Practice 6Practice 8

2 Evaluate/Construct- Students collectively decide which group member’s engineering design should be built. Rational for the decision should be documented. Students will build the prototype of the solar cooker.

HSPS3-3HS-ETS1-3Practice 2

3 Test/Peer Review/Graph- Students will use the first part of the class to test their prototype solar cooker. While students are collecting data, students will conduct a peer review as described in session 3 above. Students will use the remaining class time to construct the X-Y scatter graph of the data.

Homework: Students will review data and peer reviews to modify the group design of the solar cooker.

HSPS3-3Practice 3Practice 4Practice 5Practice 6Practice 8

4 Modify Prototype/Test- Students will decide upon the modification to be made to the solar cooker prototype. Students will modify the prototype to reflect the new design. Students will conduct test on the new prototype and collect data on how the temperature of the water changes over time.

Homework: Students will construct an X-Y scatter graph, add a line of best fit, and derive the algebraic equation that represents the line.

HSPS3-3Practice 2Practice 3Practice 4Practice 5

5 Completion of Design Journal-See session 7 above.

HSPS3-3Practice 4Practice 6Practice 7Practice 8

D R A F T 17

Teacher Resources:Video to Show Students:“Yes We Do Solar Cook”https://www.youtube.com/watch?v=2_lA4I9__aI.

Article for Students:“Principles of Solar Box Cooking Design.”http://solarcooking.org/sbcdes.htm

Additional Resources to Consider:http://solarcooking.org/sbcdes.htmhttp://reta.nmsu.edu/modules/scooker/lesson/s_cooker.swfhttp://www.solarcookers.org/basics/how.htmlhttp://science.howstuffworks.com/environmental/green-science/solar-cooking.htm/printablehttps://sites.google.com/site/suncookers/the-science-of-solar-cooking

D R A F T 18

Considerations:This curriculum-embedded performance task was created with the Next Generation Science Standards (NGSS) in mind. The NGSS emphasis eight science and engineering practices which are the focus of this performance task. Adding engineering components into a class requires time. This task can be modified as the teacher see fit, however the basic engineering principles which allow students to make engineering decisions based upon scientific research, test their designs, then modify their prototype based upon the results are essential components of this task.

The materials list provided are suggested materials you may wish to provide to your students. Teachers are not expected to have all of these materials available to students but should provide a sufficient amount of choices students can select from. Students should only use materials provided by the teacher to build the solar cookers.

Ideal testing of the solar cookers will occur outside when the sun is it’s strongest (early fall or late spring). Solar cookers can be tested during the winter but results will not be as drastic. If the weather is poor, heat lamps can be used to simulate sunlight. Teachers are provided with flexibility to determine how much time student have to heat the water. It is suggested to provide as much time as possible for two reasons. This will allow for higher water temperatures to be achieved and it will also allow for more time for students to critique and learn from other group’s designs.

Multiview drawings (top, front, side) are the ideal way to display the drawing of the created prototype. If time is a major constraint, one drawing can suffice. Students with strong math background should be asked to draw their multiview drawings to scale.

Using mathematics and computational thinking is an integral component of the science and engineering practices. Students should graph their results with an X-Y scatter graph using a graphing program such as Excel or Logger Pro if available. If these or a similar program is not available, students may generate the X-Y scatter graph using graph paper. Students should use the slope of the line generated to help them evaluate their results when compared to other groups.

The design journal students are asked to create can be done on computers or on paper. A template has been provided on pages 10-18 of this document for students that cannot access computers to generate the journal. A rubric for grading the journal has been provided to the student in the student material section. The teacher may choose to break up the journal into smaller assignments or have the student submit the journal at the end of the project based upon the needs of the students.

D R A F T 19

Name________________________________________________Period_____________

Solar Cooker Engineering ChallengeDesign Journal

Identification of the engineering challenge:In the space below identify in detail the engineering challenge you are faced with. You should clearly identify the given constraint and specification you have been held to.

Research: In the space below explain how solar cookers serve as an example of energy transformations along with the specific energy transformations that are occurring in a solar cooker. Identify the benefits of using solar cookers over traditional means of cooking should be explained. Identify the parts of a typical solar cooker as well as how they function to create a working solar cooker. Areas of solar cookers that lead to a loss of energy to the surroundings should be identified.

D R A F T 20

Multiview Drawings:In the gridlines provided, create multiview drawings of your prototype. The drawings should be labeled to include materials used as well as dimensions in metric units.

Top

Front

Side

D R A F T 21

Rationale for Design: In this chart you should justify the engineering decisions that were made when you designed your solar cooker. For example if you decided to make your solar cooker out of foam board instead of cardboard, the scientific reasoning for that decision needs to be explained. Please do this in the chart below.

Engineering Decision Scientific basis for your decisions

Prototype Image: Please allow for teacher assessment of your finished prototype here or insert images of the top, front, and side of your prototype.

Test Results: Data Table:Create a data table in the space below of how the temperature of the water in your solar cooker changed over time.

D R A F T 22

Graph: Create a graph in the space below of how the temperature of the water in your solar cooker changed over time.

Equation: Using your line of best fit, identify the y-intercept and the slope of the line. From this information, express the equation of your line of best fit in y=mx + b form (m=slope and b is the y-intercept).

Class Data:Evaluate other group’s solar cookers. Make note of their design differences and the results of their test, particularly the slope of their line.

Group Engineering Design Test Results

D R A F T 23

Rationale for Revised Design: Indicate the engineering change you will make to your prototype. Provide at least two reasons (at least one should be based on data collected) you decided to implement this change to your prototype.

Revised Multiview Drawings:Top

Front

Side

D R A F T 24

New Test Results: Data Table:Create a data table in the space below of how the temperature of the water in your solar cooker changed over time.

Graph: Create a graph in the space below of how the temperature of the water in your solar cooker changed over time.

D R A F T 25

Equation: Using your line of best fit, identify the y-intercept and the slope of the line. From this information, express the equation of your line of best fit in y=mx + b form (m=slope and b is the y-intercept).

Class Data:Evaluate other group’s solar cookers. Make note of their design differences and the results of their test, particularly the slope of their line.

Group Engineering Design Test Results

Final Evaluation of Solar Cooker:Evaluation of prototype changes:In the space below evaluate if the changes made to your solar cooker improved its performance. Support your claim with specific evidence collected.

Limitations:In the space below describe at least two limitations to your solar cooker.

Further Changes:In the space below indicate at least one further change that could be made to your solar cooker prototype. What is the reason that you would make this change?

D R A F T 26