Though it is well known that museums should embrace digital learning, many museum websites have not fully utilized digital learning resources, especially in interactive ways. In fact, in a survey of 225 websites of selected U.S. cultural institutions that have informal science education at the heart of their operations, we found that just 5% of the websites offer interactive learning resources. Based on these findings, we present an overview of interactivity in digital learning and discuss the rationale for interactive learning units on museum websites: adding to museum online offerings, connecting formal and informal learning, motivating learning in bite-sized portions and repurposing content.