i-Ready is an English Language Arts (ELA) and mathematics instructional program for Grades K-8 students featuring an individualized plan for instruction based on each student's performance on an online, computer-adaptive diagnostic assessment. Once students complete the diagnostic assessment, i-Ready builds a unique lesson plan with a differentiated starting point for every learner based on their overall and domain-level placement. i-Ready allows teachers to add lessons and/or adjust the lesson sequence provided to individuals or groups of students. Lessons provide explicit instruction and extensive practice, offer supportive feedback, with the goal of building conceptual understanding for learners of all levels. Curriculum Associates recommends that all students using i-Ready maintain an average usage of 30-49 minutes per week and pass 70% of lessons during a school year. The purpose of this study is to separately ascertain for ELA and mathematics the extent to which increases in usage are associated with increases in achievement (Curriculum Associates, n.d.). The i-Ready Diagnostic test is administered three times per year, in the Fall (AP1), Winter (AP2), and Spring (AP3).