A toddler pushes a plastic car across the floor. A young boy struggles to pull a wagon loaded with wooden blocks. A girl notices that her bicycle wheel rubs on the fender, making the bike difficult to ride. From an early age, children experience the principles of motion when they play with wheeled toys or use vehicles for recreation.

Children are also natural designers and builders. They play with whatever materials are at hand and experiment freely to try out their ideas. Children who have access to building sets learn to manipulate the parts, make changes to an object they have built, or add interesting features to it.

Motion and Design combines these two interests of young children. It enables students to analyze the motion of vehicles they have built, investigate how forces affect a vehicle's motion, and design vehicles that are propelled by stored energy.

Lesson 1 is designed to reveal to the students, and those working with them, what they already know and what questions they have about motion and design. After becoming familiar with a building set, students design and construct a simple vehicle. In Lesson 2, students make a drawing to record the vehicle they designed and built in Lesson 1 and then build a standard vehicle from a technical drawing. Students' work in Lessons 1 and 2 serves as a pre-unit assessment that is matched to corresponding assessment activities at the end of the unit.

In Lesson 3, students use the standard vehicle they built in Lesson 2 to investigate how a vehicle moves when acted on by various forces. Students create a system of falling weights to pull the vehicle. By observing how the vehicle moves when a weighted string pulls it, they can investigate how a force can change a vehicle's motion. In Lesson 4, students modify the vehicle so that it can carry a load and then investigate how different loads affect the way the vehicle responds to a force. Students measure the time it takes the vehicle to move a distance and plot the results. These two lessons set the stage for a design challenge in Lesson 5, an embedded assessment in which students must build a vehicle that moves a specified distance in a specified time. Students present their results to the class and discuss the strategies they used to meet the challenge.

In Lessons 6 through 12, students investigate self-propelled vehicles. In Lesson 6, they are challenged to move their standard vehicle with the energy stored in a twisted rubber band. Students then freely investigate what happens when they attach the rubber band to the vehicle in various ways. In Lesson 7, students perform a controlled investigation in which they determine how the number of times they wind the rubber band around the axle affects the distance the vehicle moves. This activity introduces the concept of stored energy and helps students understand that the more energy stored in the twisted rubber band, the greater the change in the vehicle's motion.

In Lesson 8, students evaluate the design of their axle-driven vehicles, looking specifically at friction and design features that may enhance or oppose the vehicles' motion. Through discussion of how parts of the vehicle can rub together, students grasp the idea that friction affects vehicle performance and must be considered during design. In Lessons 9 and 10, students extend their knowledge of friction as they design vehicles with a sail and test the effects of "air friction," or air resistance, on the motion of their vehicles.

In Lessons 11 and 12, students apply what they have learned about the physics of motion and the process of design to the building and testing of a vehicle driven by a propeller. Using a three-view technical drawing in Lesson 11, students build a propeller-driven vehicle. By modifying independent design features of the propeller-driven vehicle in Lesson 12 and determining the effects of each design modification on the vehicle's motion, they engage in a more challenging design problem.

Lesson 13 introduces students to another design requirement--cost. Given the value of each building piece, students determine the total cost of their propeller-driven vehicles and then redesign them to reduce this amount. After retesting their vehicles to ensure they still move and making further modifications if necessary, students determine the final reduced cost of their vehicles.

Lessons 14 through 16, a second embedded assessment, enable students to apply what they have learned throughout the unit to a final design challenge. In Lesson 14, students work in cooperative teams of six and choose one of several design challenges. In a planning session, they decide on the vehicle design, system for moving the vehicle, cost, and method of testing. Then they sketch their proposed vehicle. In Lesson 15, each team builds, tests, refines, and retests its vehicle, making certain it is within the proposed budget. Teams then present their final design solutions in Lesson 16 and conclude with a reflective writing activity.

Following Lesson 16 is a post-unit assessment that is matched to the pre-unit assessment in Lesson 1. The additional assessments provide further questions and challenges for evaluating students' progress, including the examination of real-world vehicles and the development of portfolios in which students organize and display a selection of their work from the unit.

This is a rich unit for students. Just as engineers do, students test their vehicle designs and repeatedly evaluate and refine them until the designs meet specifications. They apply physics concepts to solve practical problems. Their introduction to technical drawing improves their record-keeping skills and extends their visual perception. As a class, students share in the creativity of solving problems, testing ideas, and presenting results. Finally, students reflect on their work throughout the unit and grasp how they can apply these problem-solving skills and concepts in their own world.