Measuring a teacher’s impact on student learning can be challenging. After all, students start the year at different skill levels, and they all face different factors inside and outside the classroom that affect how they learn. At its core, IVA is a way of dealing with these challenges. It helps us estimate the teacher’s impact on student learning as opposed to the impact of other factors, such as students’ prior skill level, the resources they have at home, any learning disabilities they may have, or their classroom composition. In short, IVA helps us understand what the teacher did, apart from everything else.