This discussion-based lesson is designed to support Year 6 students in their initial understanding of using letters to represent numbers, expressions, and equations in algebra. The three level framework is designed for: (1) making thinking explicit, (2) exploring each other's solutions, and (3) developing new mathematical insights. In each level of the discussion, students are connecting prior knowledge to new knowledge and making new mathematical connections. The results from the whole class discussion is to develop "big mathematical ideas" that students can transfer to other problems and situations.