This article describes a lesson rooted in "tinkering," an approach to learning that encourages the use of authentic, hands-on experience to develop an understanding of content and physical materials. There were several desired outcomes for this lesson. First, the authors felt that tinkering was an appropriate approach to investigating the disciplinary core idea (DCI) for balanced and unbalanced forces while at the same time exploring common tools. Second, the authors wanted to engage students with an imaginative design task that featured open-ended inquiry. Third, they wanted to create a learning experience that would help students see themselves as real-life problem solvers while addressing core science content. The lesson was designed as part of a third-grade unit on forces and motion and uses materials from a Levers and Pulleys kit produced by Delta Education. Since the removal of simple machines as an explicit "Next Generation Science Standards" ("NGSS") topic, this kit can often be found unused in school closets even though it is a favorite with many elementary teachers and contains a variety of useful materials. Thus, this lesson represents a creative use for the underutilized resources in this popular kit. The lesson is designed to take approximately 120 minutes and can be completed as a whole segment or spread over multiple class periods.