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In the JetToy Challenge, a fictitious toy company called EarthToy Designs presents the challenge in the form of a letter. The company wants students to provide a variety of interesting designs for a new line of balloon-powered vehicles made from inexpensive, common materials that will appeal to other children. Working in design teams, students will build and test model JetToys using different nozzles, and collect and analyze data to understand the effect of nozzle size on the performance of the toys. They will create other designs and test them, then give a formal presentation of their final JetToy designs.

Lesson 1 – Introducing the JetToy Challenge (45 min)

Students receive a letter from a fictitious toy company inviting them to create different JetToys using simple materials. Students discuss the requirements described in a letter from EarthToy Designs. They are introduced to the engineering design process and the scope of this design challenge: to build a JetToy, to figure out how it works in order to predict its behavior, and to use this knowledge to design customized JetToys that meet specific performance characteristics and design goals.

Lesson 2 – Building and Testing the JetToy Chassis (90 min)

Students are organized into design teams that they will work in for the duration of the project. Each team receives a design log that it will use to record its work. Teams construct a chassis. After adding wheels and axles, they test their models by rolling them down a ramp and observing their performance. Students then modify and test the vehicles until they roll straight and can go a specified minimum distance.

Lesson 3 – Adding the Balloon Motor (90 min)

Students assemble a balloon motor and add it to the chassis they built in Activity 2. The balloon motor consists of a short piece of tubing (the nozzle) fastened inside the neck of a balloon by a rubber band. Students then do informal experiments with the balloon-powered vehicle and observe its behavior. They come across several engineering issues concerning the mounting of the balloon motor, such as how best to attach the nozzle to the vehicle and how to keep the balloon from flopping around or onto the wheels. Students are encouraged to add features that solve these problems and improve the vehicle’s ability to travel straight and far. These new features are created from simple materials: poster board, masking tape, and straws. Students record their ideas and solutions and note the changes in performance. They repeat this modify-and-test cycle with the goal of designing vehicles that roll straight and can go a specified minimum distance.

Lesson 4 – Sharing First Results (45 min)

Students share the data and experiences they have collected from their experiments so far. They talk about what makes a vehicle roll straight and smoothly. They share their ideas for solving problems they had in mounting the balloon motor and making their vehicles roll well. They learn what physical phenomena are involved and how to express their ideas using the correct scientific terminology. The basic properties they are dealing with include forces, friction, and inertia. An object moves because a force acts on it. The forces they have observed are gravity (rolling down the ramp) and air pressure (from the balloon motor). Friction is another force which acts to resist motion and use up energy it slows down all moving things. Students have learned that they can control friction by keeping parts from rubbing against each other. Inertia is the physical property that keeps an object moving after the accelerating force is gone, as when the chassis continues to roll past the ramp, or after the balloon has deflated.

Lesson 5 – Revising the Vehicle (45 min)

Students revise their JetToys to incorporate features that seemed to be successful when tested and discussed in previous sessions. The new features will be made from the same materials as before: poster board, tape, straws, and paper clips.

Students assemble balloon motors in three sizes and make weights out of stacks of pennies, then experiment informally with them. Based on their observations of the vehicle’s performance, they will begin to get a sense of the effects of different balloon motors and added weight.

The goal of revising the JetToy is to create a vehicle that is sturdy enough to be used for formal experimentation

Lesson 6 – Designing Experiments (45 min)

Students share their hypotheses about factors that influence performance of the JetToys. They make lists of factors they can and cannot control. Controlled experiments are introduced and discussed. Students suggest variables to test and review the data sheets and graphs they will use to record their experiments.

Lesson 7 – Formal Testing (90 min)

In the last activity students were introduced to the rationale and procedures for formal testing with controlled variables. In this activity they test distance and time for the variables of nozzle size and weight added. Teams will all carry out the same tests, each with its own vehicle. Because the design teams vehicles are different, their results will vary. However, the general trends should be the same.

Lesson 8 – Reviewing Experimental Data (45 min)

Students share the data they graphed from experiments with their vehicles. They compare the graphs made by each design team and look for patterns in the data. They draw conclusions that serve as a basis for designing a fleet of JetToys that have different performance characteristics. The class discusses some of the physical principles involved, and students are introduced to conventional scientific terminology for the phenomena they have been observing.

Lesson 9 – Designing a JetToy (45 min)

Student design teams use the information from their discussion in Activity 8, Reviewing Experimental Data, to design a JetToy that they think will meet the requirements given in the letter from EarthToy Designs. On a design specifications sheet, they state the performance the team wants its JetToy to have, draw their JetToy, and describe why they think these characteristics will meet their performance objectives.

Lesson 10 – Building and Testing a JetToy (90 min)

Design teams build a JetToy based on their design specifications. They test their models and make adjustments to their designs as needed. They decorate the JetToys based on the drawings they made on their design specifications.

Lesson 11 – Presenting JetToy Designs (45 min)

Student design teams share their final JetToy designs with the class and, if possible, invited guests. Teams present their JetToy Design Specifications and test results. Each team demonstrates its model to show how well it meets its JetToy Design Specifications. The class discusses the relationship between the design of the models and their performance. Students then reflect on how their understanding of the JetToy has grown since they began the challenge.