Response-to-intervention (RTI) systems posit that Tier 1 consists of high-quality general classroom instruction using evidence-based methods to address the needs of most students. However, data on the extent to which general education teachers provide such instruction are rarely collected. This missing instructional data problem may result in RTI decisions being made without sufficient evidence. Recent advancements in the conceptualization and measurement of opportunity-to-learn (OTL) can operationalize and assess key aspects of Tier 1 instruction in ways that are scalable and formative for teacher practice. In this article, we provide a rationale for collecting and using OTL data via an online teacher log called MyiLOGS (My Instructional Learning Opportunities Guidance System). We summarize three MyiLOGS studies focusing on general and special education classrooms and students with and without disabilities. We conclude by contextualizing these studies' findings for purposes of Tier 1 instructional data collection and discuss the need for future research.