In this activity, learners consider how a simple machine, a lever, turns a small push or pull (a small force) into a larger--or stronger--push or pull (a larger force). Learners then apply this concept to designing a model seesaw. In small groups, they explore a variety of materials in an open-ended process of building, testing, and revising. The challenge is set in an age-appropriate context of addressing one or more real-world challenges, such as designing a seesaw on which two people of different weights (e.g., a child and parent) or a person using a wheelchair can ride. This activity is part of a curriculum designed to engage learners in hands-on engineering challenges.