Students construct paper sailboats and test the effect of different sail shapes, sizes, and construction methods to meet specific performance criteria. Friction, forces, the effect of surface area and design are some of the physical phenomena students encounter in this challenge.
The Skimmer Challenge has been designed to supplement the curriculum of an elementary (4-6) science or math teacher. Like all AWIM challenges, the Skimmer 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 Skimmer Challenge, students are introduced to a model Skimmer presented by the fictitious toy company EarthToy Designs, whose specialty is making toys out of recycled or recyclable materials. The design of the toy is incomplete and suggestions for variations on this toy are requested from student design teams. These teams provide many of the services required for the toy product to move to the next stage of development. They will test the model with different sails to understand how sail characteristics affect the way it moves, create other designs and test them, and then give a formal presentation of their final skimmer designs.
Students acquire and then apply their knowledge of Skimmer performance to create an interesting toy. Students may choose to make Skimmers that sail fast or slow, turn or go straight. The sails may be functional, artistic, or even whimsical. In designing these new sails, students have control of the shape, size, balance of the sail, and the weight and balance of the Skimmer.
Students working on this design challenge find that there is no one solution to any particular problem. There are many ways to configure the sail so that the Skimmer travels a great distance, does a turn, or carries a load. However, to sort through all the design factors and create a design for a particular purpose, students will need an understanding of how each factor affects performance. This understanding—based on their hands-on experimentation, gathering and understanding experimental data, and classroom discussions —sets the stage for student teams to create and refine their own skimmer designs.
Lesson 1: Introducing the Skimmer Challenge (45 min)—Students receive a letter from EarthToy Designs, Inc., a fictitious toy company, challenging them to design a toy "skimmer." This sets the context for their engineering design experience. First, students read the letter that explains the scope of the design task with which they will be engaged in the unit. Then they see a demonstration of a prototype that gives them an idea of how a skimmer looks and behaves.
Lesson 2: Building The Skimmer (90 min)—Students join a design team and, with their team, build a skimmer in three steps. First, they build a hull using the Skimmer Hull Pattern and the instructions on Building the Skimmer Hull. Next, they make a stand to hold the skimmer's sail using a paper clip and the instructions on Making a Sail Stand. Finally, they attach a 3 x 5 index-card sail to a drinking straw mast and mount the mast on the skimmer sail stand. Design teams then test this skimmer in front of a fan and record data on its performance in their new Team Design Log.
Lesson 3: Our First Sail Designs (90 min)—As a challenge pretest, each student designs a sail and writes down his or her thinking for the design. Design teams meet to share their thinking and then, as a group, determine a shape they think would make their first sail design a good one. The initial focus is on making the skimmer go far and straight. They draw the sail on oaktag, cut it out, trace it on a sheet of graph paper, determine its area, and attach the sail to their skimmer. They also learn how to use the Skimmer Test Log to record their test results. Each team then tests its skimmer's performance using the log to record data on each sail design.
Lesson 4: Sharing Our First Results (45 min)—Design teams share their test results and observations on their preliminary sail designs. The class looks for patterns in the relationship of sail characteristics, including shape, area, and location on the skimmer, and how these affect the distance the skimmer travels. Which characteristics seem to be related to the skimmer traveling far and straight? Which characteristics seem to be related to traveling a shorter distance? The class discusses whether there is a way to determine how the different sail characteristics account for the performance observed. How do the characteristics of sail size, shape, height, placement on the hull, or other characteristics the class may determine, interact to determine a skimmer's performance?
Lesson 5: Deciding What to Test (45 min)—In this activity, students discuss how they might carry out experiments to test each of the skimmer characteristics on the list they made in Activity 4, Sharing Our First Results.
Lesson 6: Testing Sails (90 min)—To begin testing skimmer sails, all design teams test the characteristics of sail area and sail shape. After the class performs these tests, design teams select the tests they want to perform from the list of proposed tests the class made in Activity 5, Deciding What to Test.
Lesson 7: What We've Learned About Sails (90 min)—As a class, students discuss the results obtained from the design teams' testing and use test data to draw conclusions. They make a chart of the results that indicate the settings or features that resulted in the longest and straightest performance, as well as any features that helped the skimmer turn reliably. They then discuss their hypotheses about the forces that cause the characteristics to have the effects they discovered.
Lesson 8: Designing a Skimmer (45 min)—In this activity, student design teams use the information from their discussion in Activity 7, What We've Learned About Sails, to design a sail that they think will meet the requirements given by the letter from EarthToy Designs. On a Skimmer Design sheet, they state the performance the team wants its skimmer to have, draw the sail they plan to use, and to describe why they think these characteristics will meet their performance objectives.
Lesson 9: Building and Testing a Skimmer (90 min)—Design teams make a skimmer sail, or add other features, based on the Skimmer Design sheets they completed in Activity 8, Designing a Skimmer. They test their models and make adjustments to their designs as needed. They decorate the skimmers based on the drawings they made on their Skimmer Design sheets. Teams begin to plan their presentations of their skimmer prototype.
Lesson 10: Skimmer Presentations (45 min)—In this activity, student design teams share their final skimmer designs with the class and, if possible, invited guests. Teams will present their Skimmer Design sheets and test results. Each team demonstrates its model to show how well it meets the Skimmer 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 skimmer has grown since they began the challenge.