Formative feedback is well known as a key factor in influencing learning. Modern interactive learning environments provide a broad range of ways to provide feedback to students as well as new tools to understand feedback and its relation to various learning outcomes. This issue focuses on the role of formative feedback through a lens of how technologies both support student learning and enhance our understanding of the mechanisms of feedback. The papers in the issue span a variety of feedback strategies, instructional domains, AI techniques, and educational use cases in order to improve and understand formative feedback in interactive learning environments. The issue encompasses three primary themes critical to understanding formative feedback: 1) the role of human information processing and individual learner characteristics for feedback efficiency, 2) how to deliver meaningful feedback to learners in domains of study where student work is difficult to assess, and 3) how human feedback sources (e.g., peer students) can be supported by user interfaces and technology-generated feedback.