Students often confuse the functional differences between motion "transmission" and "transformation" systems. Students find it difficult to conceptualize differences between the specific systems. In this article, the author describes a technology and engineering unit that incorporates problem-based learning (PBL) to assist students in the design and construction of a prototype, illustrating the concepts of motion transmission and motion transformation. The technology activities follow the principles of Ambitious Science Teaching, including: (1) engaging students with important science ideas; (2) eliciting students' ideas and making visible what students currently know about the science being taught; (3) guiding sense-making talk around investigations and lab activities to support ongoing changes in thinking; and (4) developing evidence-based explanations by scaffolding students' efforts to put everything together. By the end of this lesson, students will be able to explain the choice of motion transmission and motion transformation systems in a technical object, and use systems that allow for speed changes in technical objects. Student work includes a design plan, a technical drawing, and a working prototype. The lesson, designed for grade levels 9 and 10, requires approximately 375-450 minutes of class time.