 There has been decades now actually, 20 plus years of research on digital annotation or annotation occurring in online web-based computer-supported spaces. And notably enough, hypothesis is perhaps the tool that has been researched the most. There's now been quite a few years worth of pretty dedicated research across disciplines, interdisciplinary research about how hypothesis as a form of social annotation does support student learning. But again, there's really decades now of social annotation research, research about this type of collaborative learning in online spaces. But no tool in my reading of the literature has actually been used as extensively and now researched as extensively as hypothesis has. And I think that's really a testament to the organization, a commitment to open technologies, the kind of flexibility with which now hypothesis can be used across a variety of learning environments, and then just some of those social and technical affordances that really do productively aid students and their learning.