The objective of this action research study was to explore the use of formative assessment (daily quizzes), including identification of student weaknesses or lack of understanding, along with instructional correctives that are different from previous instruction, to help students attain the intended learning goals. Part of the exploration was to determine if the use of this formative assessment focusing on "error types" improved student achievement. The analysis of the data from this study as compared to other "error type" studies supports the conclusion that student achievement does improve when systematic errors are identified from the formative assessment and analyzed. This data was then used to respond to individual learning needs. The majority of the errors studied resulted in improved student achievement after these errors specifically were addressed with focused instruction guided by the formative assessment.