The field of K-12 education is being transformed, with an influx of students, including those with identified disabilities, engaging in blended and fully online learning. While online learning shows promise for students with disabilities through flexible content and personalised instruction, concerns regarding accessibility and appropriateness of online learning for this population still exist. In order to examine this concern, researchers developed and used a Universal Design for Learning (UDL) Scan Tool to measure lesson content and alignment with UDL principles, guidelines and checkpoints. Four hundred and seventy-eight math, science and world history Khan Academy lessons were randomly selected and evaluated for this study. The paper highlights the results of the study, in terms of the lessons' alignment with UDL principles and guidelines, as well as a discussion on limitations and future research.