Motorized Toy Car

Students develop new designs for electric gear driven toys. The students are involved in writing proposals, drawing sketches, and working with models to develop a plan to meet a specific set of design requirements. Force and friction, simple machines, levers and gears, torque and design are the core scientific concepts covered in this challenge.

The Motorized Toy Car Challenge has been designed to supplement the curriculum of teachers and is intended for seventh-grade students whose teachers are using a multidisciplinary approach. Like all AWIM challenges, the Motorized Toy Car Challenge will join together teachers, students, and industry volunteers in an exploration of physical science while addressing essential mathematic and scientific concepts and skills.

In the Motorized Toy Car Challenge, a fictitious toy company called Mobility Toys Inc. presents the challenge in the form of a Request For Proposal (RFP). The company is interested in receiving new designs for moving toys. The toy company sends the RFP to the class requesting written proposals, sketches, and working models of designs that meet a specific set of requirements. Over the course of the curriculum, a variety of activities will prepare the students to develop a proposal and a prototype for a toy of their own design. The students must work in teams and as a team to complete the requirements stated in the letter. The program culminates in student presentations of their working models and a discussion of the design teams' efforts to address the challenge.

Students begin the Engineering Design Experience (EDE) process with goal setting activities that encourage group building and identifying tasks. Students continue to work in teams to develop the prototypes of models through which they explore many of the science and engineering concepts central to the toys' successful performance. Teacher-directed activities in the science, mathematics, technology education, social sciences, and language arts classes will cover the basic concepts and skills needed to understand the principles behind the prototypes and apply them when building the models. These lessons include demonstrations and hands-on experience examining force and friction, simple machines, levers and gears, torque, etc. In mathematics, students apply an understanding of ratio and proportion as they explore the relationship between gear ratios and the radius of a wheel. Through gathering information from the client and eventual "customers" and conducting controlled experiments, the students explore data collection and retrieval techniques and apply basic statistical analysis. In addition, students apply their public speaking and writing skills as they prepare a workable proposal and presentation.

Lesson Plan Overview

Lesson 1: Reading and Evaluating the Request for Proposals (RFP) (90 min)—Students will receive a Request for Proposals (RFP) from the director of new product development at Mobility Toys, Inc. (MTI), a fictitious toy company. The RFP explains that MTI is looking for new designs of a toy to add to their current product line and is inviting design groups to submit proposals and prototypes of their ideas. Students will carefully read the RFP to determine what is expected of design teams and what is needed to meet the challenge. They use the Evaluating the RFP Log Sheet to begin to analyze what the RFP is asking them to do. They write down questions for a volunteer engineer who will be visiting the classroom.

Lesson 2: Meeting an Industry Volunteer (45 min)—A volunteer engineer visits the class to talk to students about how engineers work when they design things. The volunteer's conversation with the students focuses on the engineering design experience, especially two important aspects of the design process that students will encounter: working in design teams and using design logs to keep careful records of their work. Students can ask the representative the questions they have prepared about the RFP.

Lesson 3: Designing a Team Name, Logo, and Slogan (45 min)—Students are divided up into design teams. The class discusses how to work in teams, and the roles they will take in their teams. The teams collect examples from magazines of company logos and slogans, and make these into a collage. They discuss how companies use logos and slogans to appeal to customers. Students then work in their design teams to design a team name, logo, and slogan.

Lesson 4: Using Design Logs (45 min)—In this unit student design teams will record their work in Design Logs. This activity introduces students to the importance of keeping a Design Log, and ways they can use their Design Logs to keep a record of their work and to reflect on their designs.

The activities in the unit suggest specific ways the Design Logs can be used. You may want to suggest to students other ways they can use the Design Logs. For example, students will need to use data recorded in their Design Logs to document the development of their vehicle designs as part of their final presentations. Students can also use the Design Logs to record consumer data they collect, and to record questions they want to pose to other students, the teacher, the volunteer engineer, or others.

You can use students' Design Log entries to assess their understanding of content, design process, and writing skills.

Lesson 5: Identifying the Customers (45 min)—Students analyze the RFP letter from MTI to begin to determine the different kinds of customers and their needs.

Lesson 6: Seeing the Big Picture (45 min)—In this activity design teams analyze the RFP letter again to determine how to respond to the challenge it presents. Students will use the information they gathered from the Reading and Evaluating the RFP and the Identifying the Customers activities to answer several fundamental questions. This information will eventually help to define specific tasks that are part of the overall design experience.

The RFP letter defines minimum performance as a rate of travel of at least three meters in three seconds, the ability to climb a 15-degree slope for one meter in two seconds, or climb a 30-degree slope for one meter. Most student teams will be able to develop a model car that easily meets one or more of these criteria. The RFP also stresses consideration of unique models as long as the characteristics are of interest to the customer. Design teams consider the potential customers, and may develop and implement a customer survey, interpret the results, and base their final design on meeting customer needs as well as engineering feasibility.

Lesson 7: Creating a Design Checklist (45 min)—This activity is provided for classes that need more time to plan how they will approach the challenge. It can also serve to allow motivated students greater leeway in structuring their own activities to gain the necessary understanding, skills, and information to meet the challenge.

In this activity design teams begin to make concrete steps toward responding to the RFP. They will describe tasks that will help them design and build a prototype, find out what might interest the customers, or learn a specific skill such as conducting an interview or writing a resume.

Design teams will develop a checklist of tasks and decide how to accomplish them. They may assign responsibility for tasks to a specific team member or decide that they want to accomplish the tasks together.

Lesson 8: Looking at Gears in Bicycles (45-90 min)—In this activity, students are introduced to the use of gears in a context that will be familiar to most of them: a bicycle. They connect their experience of bicycle riding to the idea that gears can be used to change the speed and torque of a rotating wheel. They examine the effects of different gear combinations on a derailleur bicycle. They talk about their experiences using the gears on a bicycle to ride in different conditions.

Lesson 9: What We Know About Gears (45-90 min)—This activity acquaints students with some of the machines that use gears. Students begin by sharing what they know about where gears are used and how they work. They discuss the observations they made about the bicycle in the last activity.

Lesson 10: Introducing the Gear Materials (45-90 min)—This activity acquaints students with the gear materials they will use to build their toys. They are introduced to the gears and how to mount the gears on axles on the vehicle frame. They then explore how different gear combinations give different rates of rotation. They make qualitative observations about how pairs of gears behave, and share their observations.

Lesson 11: Recording Gear Rotations (45 min)—In the previous activity students started to explore different kinds of gear trains and to become acquainted with how gears can change the speed of rotation. In this activity students use a table to record the numbers of rotations of both gears in a meshing pair. They will use this table in the next activity to develop the concept of gear ratio.

Lesson 12: Developing the Gear Ratio Formula (45-90 min)—In this activity students make observations about the rotation relationships in the tables they made during the Recording Gear Rotations activity. They explore these relationships as constant values that depend on the number of teeth on the two gears. They are introduced to the concept of ratio as a way to express these relationships. Students derive the formula for finding the gear ratio of a pair of gears: gear ratio = teeth in driven gear/teeth in driver gear.

Lesson 13: Using the Gear Ratio Formula (45-90 min)—Students use the gear ratio formula that was introduced in the Developing the Gear Ratio Formula activity. They calculate gear ratios given the number of teeth on two meshing gears. They also find the gear required to produce a given gear ratio.

Lesson 14: Measurements and Ratios in Wheels and Gears (optional) (45-90 min)—This is an optional activity that gives students more exposure to and practice with ratios. Students make measurements of the diameter and circumference of wheels and gears. They calculate the ratios of these measurements. They look for constant ratios of these measurements to one another.

Lesson 15: Adding a Motor and Wheels (45-90 min)—Students add a motor and wheels to their gear trains to make a motorized test vehicle. They troubleshoot their models and share their designs with the class.

Lesson 16: Measuring Performance: Speed and Wheel Rim Force (45-90 min)—In this activity each design team is assigned to build a motorized test vehicle with a specific gear ratio, then gather data on its performance. They build gear trains on their vehicle frame to connect the motor to the wheels. They record the gear ratio, measure the speed of the vehicle over three meters, and use a spring scale to measure the force at the rim of the wheel. They look for relationships among the data they record.

Lesson 17: Compound Gear Trains (45-90 min)—Students are introduced to compound gear trains—gear trains that have more than one gear on an axle. They build compound gear trains on their test vehicles.

Lesson 18: Measuring Performance: Compound Gear Trains (45-90 min)—In the Compound Gear Trains activity, design teams built test vehicles that had compound gear trains. In this activity, design teams measure the performance of these test vehicles: the rim force at the wheel, and the time the vehicle takes to go 3 meters. Students record performance data as they did in the Measuring Performance: Speed and Wheel Rim Force activity. They look for patterns and correlations in the data.

Lesson 19: Multiplying Fractions to Calculate Gear Ratios (45-90 min)—This activity offers an opportunity for students to use fraction multiplication to calculate the overall gear ratio in a compound gear train. Students use fractions to represent each gear ratio in a gear train. The class reviews how to multiply fractions. Students multiply the gear ratio fractions to find the overall ratios for gear trains.

Lesson 20: Measuring the Rim Forces of Individual Gears (45-90 min)—Students have seen that different gear ratios produce different amounts of rim force. Students investigate properties of the three sizes of gears in the materials kit. They investigate the relationship between the size of the gear and the amount of force at the rim.

Students measure the rim force transmitted by the three different size driver gears. Students mount each of the driver gears, in turn, on the motor shaft. They attach a string to the gear, which winds up on the gear as the motor turns. Students use a spring scale to measure the force each gear exerts on the string. They will find that the smaller the gear, the greater the force it exerts on the string.

Lesson 21: Torque and Lever Arms (45-90 min)—Students continue to explore the concept of torque, the tendency of a force or forces to cause rotation. Torque is measured as the product of a force acting across a lever arm. They measure the lever arms of the three gears, then multiply the lever-arm values by the force values they gathered in the Measuring the Rim Forces of Individual Gears activity. They see that the product is very close for the three gears, indicating that the torque transmitted by the motor is the same for all three gears.

Lesson 22: Exploring Body Materials (45-90 min)—In this activity students investigate and evaluate possible toy body materials. They explore ways to combine materials to create a body that appeals to customers and is sturdy.

Depending on the materials you make available to students, they may examine poster board, foam core, art paste, papier-mache, aluminum foil, plastic wrap, paper straws, and craft sticks as body materials. Students may try cutting, shaping, and fastening the materials together to assess what will work best. After students have experimented with materials, they will need to decide what materials they will use to build their toy body. You may want to decide as a class on one or more materials to use, or allow design teams to choose from a variety of materials.

Lesson 23: Consumer Research: Conducting Interviews (45-90 min)—Students will learn how to gather preliminary information about the potential customers by interviewing children in the target age-group or parents with children in the target age-group. Students will be given sample interview forms, which they will have the opportunity to customize or use as a model to create their own. Students will discuss the various ways that information about the customers can be used to inform the development of a product. And, they will learn how to conduct an interview that will give them information about the buying preferences of the customers. The information students gather in the interviews will inform the surveys they will conduct later in the Consumer Research: Conducting a Survey activity.

Lesson 24: Consumer Research: Conducting a Survey (45-90 min)—Students will learn how to find out more information about the potential customers using a market survey that is given to children in the target age-group or parents with children in the target age-group. They will use the information they collected in the Consumer Research: Conducting Interviews activity to revise the sample survey provided. Students will learn how to write good questions that will give them information about the buying preferences of parents, and they will learn how to conduct a survey.

Lesson 25: Consumer Research: What We've Learned About the Consumers (45-90 min)—Students use the gear ratio formula that was introduced in the Developing the Gear Ratio Formula activity. They calculate gear ratios given the number of teeth on two meshing gears. They also find the gear required to produce a given gear ratio.

Lesson 26: Integrating and Applying What We Know (45-90 min)—In this activity, students begin to integrate and apply the understanding they gained in the Set Goals and Build Knowledge phases to create a design that will meet the RFP challenge from Mobility Toys, Inc.

Design teams meet and review the lists they made in the Seeing the Big Picture and What We've Learned About Gears activities, as well as their research findings from the Consumer Research: What We've Learned About the Consumers activity. They begin to integrate the information they have gained about the RFP, their understanding of gear ratios and performance, and their understanding of the needs of the various kinds of consumers they have investigated.

Lesson 27: Writing a Design Brief (45-90 min)—In this activity, student design teams use the information from the Integrating and Applying What We Know activity to write a design brief. The design specifications outline the characteristics of the toy they plan to design for MTI.

The design specifications include a description of the consumers for whom they are designing, the consumers' toy preferences, the type of toy (race car, jeep, truck, parade float), the appearance of the toy, and the desired performance of the toy (fast, slow, high torque, low torque).

Lesson 28: Designing a Gear Train for the Prototype (45 min)—In the Writing a Design Brief activity design teams wrote specifications for their prototype designs, including the type of toy and its intended performance. In this activity design teams use those specifications and what they have learned in the Build Knowledge activities about the characteristics of gear trains to design a gear train for their prototype toy. They present their drawings to the class.

Lesson 29: Drawing Body Designs (45-90 min)—Design teams produce drawings of their toy body designs. The students can use orthographic projections to illustrate the top, front, and side views of their toy. After students complete three or four sketches of toy designs on notebook paper, the teacher will provide the students with several sheets of white paper and graph paper. On white paper students will produce three-dimensional colored or shaded drawings of the toy. The graph paper will aid students in producing accurate drawings for size and shape.

Lesson 30: Building a Prototype (45 min)—In the first part of the Build and Test phase, design teams build a prototype based on the gear train design drawings they made in the Designing a Gear Train for the Prototype activity or the Redesigning the Prototype activity.

Lesson 31: Performance Testing the Prototype (45-90 min)—Design teams design and carry out performance testing of their prototypes to see how well they meet their own performance specifications. They complete a report for each test describing how the test was designed, and what was tested.

They report the results as data in written, numeric, and graphical form as appropriate.

Lesson 32: Interpreting Performance Test Data (45 min)—By this point in the unit students have subjected their prototype designs to a variety of performance tests. In this activity the design teams interpret the data produced by their tests to see if their vehicles meet the performance criteria. They begin to troubleshoot their designs to isolate factors that degrade performance.

Lesson 33: Redesigning the Prototype (45-90 min)—Students use the conclusions they made in the Interpreting Performance Testing Data activity to make a design they think will improve the performance of their toy. They revise their gear train design drawings. If they conducted focus group testing of their body designs, they also consider how to incorporate these results into their toy design, and revise their body design drawings.

Lesson 34: Focus Group Testing of Body Designs (optional) (45-90 min)—One way design teams can get additional consumer input on their body design is to hold focus groups. In this activity, design teams design and carry out focus group testing of their prototype body designs with potential customers. They evaluate the customers' responses to the designs and make a written report of the findings, including a description of how the test was designed, a summary of the results, and a summary of the implications for the toy.

Lesson 35: Making a Body Mock-up (45-90 min)—In this activity, design teams make a cardboard mock-up of the toy body design to make sure the body design will be compatible with the chassis they built as a prototype. The students should use the drawings from the Drawing Body Designs activity to create the basic shape of their mock-up. Ideas from magazines and newspapers may enhance the design's appearance.

Lesson 36: Constructing the Body (45-90 min)—In the Exploring Body Materials activity in the Build Knowledge phase of the unit, students investigated several body construction materials. In this activity, the design teams use their chosen body design and materials to build a body for their toy. They may make the body from any of the materials that they tested in the material test activity. Students should understand that more than one material will need to be used to build the body. To construct the body, design teams will need to consider their consumer surveys, design drawings, mock-ups, as well as their knowledge of the construction materials.

Lesson 37: Assembling, Testing, and Adjusting the Final Design (45-90 min)—Students have designed, tested, and redesigned their prototypes so that they meet the performance specifications. They have constructed a body that they believe meets the customers' needs. Now the design teams assemble the final design. They mount the body on the chassis, then test it to see how well it meets the performance specifications they wrote in the Writing a Design Brief activity.

Lesson 38: Planning for the Proposal and the Presentation (45 min)—The final presentation is the culminating activity in the design experience and a period of excitement for the students. The students in the design teams suddenly realize that a deadline is approaching and that many tasks need to be completed. In this activity, design teams review the letter from MTI and determine what they need to do in the final presentation and what they need to write in the proposal. They make a plan to get the tasks done.

Lesson 39: Preparing the Written Proposal (45-90 min)—Each design team begins to draft a proposal. They use the tasks on their completion plan to create an outline for the written proposal. Students also learn about writing styles for different paragraphs.

Lesson 40: Preparing the Oral Presentation (45-90 min)—Student teams gather and organize the necessary parts of the final presentation. They also learn how to deliver an effective oral presentation.

Lesson 41: The Final Presentations (45-90 min)—Preparations for the final presentation can be overwhelming and hectic. As the final day approaches students will rush to finish their prototypes, diagrams, speeches, and related work. In the meantime, the teachers will need to begin advance preparation for the culminating event.

Lesson 42: Reflecting on the Engineering Design Experience (45-90 min)—Students discuss the experiences they have had in the unit. They reflect on the work they did in each of the phases of the engineering design experience. They discuss what the engineering design experience is.

Lesson 43: What We've Learned About Gears (45 min)—In a discussion students review what they have learned about gears that will help them design their toy. They review the ideas about gears they had at the start of the unit and reflect on how their ideas have changed. Students begin to consider how their understanding of gears might be applied to their toy designs.

Lesson 44: Writing a Resume (optional) (45-90 min)—Student learn what a resume is, how and when it is used, and by whom. They understand that by submitting individual resumes, they are adding credibility to the written proposal submitted by their team.