They are challenged to design and build a miniature vehicle and a propulsion system that will propel it over two hills and as far as possible. Available materials include wooden wheels, straw bearings, a foamboard chassis, balloon engines, rubber band engines, and falling-weight engines. Students will be able to bring in materials from home as well, but not until they have experience with the available ones.
So that students will begin to understand what's involved in making things go, the teacher asks his/her students to bring in self-propelled toy cars from home. The students divide into small groups and "mess about" with a variety of toy cars, exploring the different aspects of their designs: method of propulsion (gear driven, rubber band powered, etc.), wheel diameter and width, tread versus no tread, and so on. Students identify what they are observing and compare and contrast the capabilities of vehicles. They try to explain why some cars work better than others. They also begin to wonder about the best ways of getting things moving and keeping them moving. They write down everything they observe and the explanations and questions that come to mind.
After messing about, they join with the class for "white boarding." Together as a class the students discuss their cars, their methods of movement, any drawbacks or advantages they might have, and questions the students have become curious about. All of the observations students made, their ideas about explanations, and their questions are recorded on the class whiteboard. The teacher's role in this stage is to help students be precise about what they observed and help them make their questions clear and understandable by others.
Now that students are curious, it's time for them to begin to address the challenge.