Understanding the prior knowledge and schema students bring to a lesson is important (Veenman, 1984), and without that crucial understanding, a teacher can create a gap between what students can actually learn and what the teacher is trying to teach (Schraw, 2006). After a pre-service math teacher realized valuable instructional time was wasted when students could not follow his instruction, he undertook this study to examine scaffolding as a problem of practice. In a high school Algebra 1 class, he taught a series of lessons during a unit on rational functions with a focus on understanding student foundational knowledge and scaffolding student understanding through intensive instruction. He analyzed the results through pre- and post- assessments. Findings include a better appreciation for the cumulative nature of math and increased student understanding after scaffolded instruction.