ABSTRACT
In 6th through 8th grade, students are tasked with developing essential understandings and skills necessary for future high school coursework in algebra. Ideally, middle schoolers will take their knowledge of numbers and operations from earlier grades and begin to reason about abstract algebraic expressions. The central problem involves a pool being filled up with water by multiple hoses that fill at different rates. Students will be asked to explain how they calculated the amount of water in the pool after a given number of minutes and eventually pushed to generating an expression to model the amount of water in the pool after x minutes. The lesson proved to elicit the desired misconceptions and varying strategies to combine like terms. The majority of students used the context of filling up a pool with water to justify why specific terms could or couldn't be combined.
