Chapter 12 opens by asking readers to identify what they know about a relatively unknown topic, and to formulate some questions about the topic; they then study the topic, identify what’s now known, and finally compare notes from before and after study. It’s surprisingly hard for one person to perceive what is given information for someone else because what we know interferes with figuring out what they know. We are in a sense cursed by our knowledge, seeing more in hindsight than is justified. The chapter describes studies with children and studies with adults showing that our current understanding blinds us to our own prior understanding and to someone else’s current understanding. In part because people have strong funds of knowledge on the topic of language, this curse or bias is especially vital to consider. For example, speakers of English unconsciously know the language’s basic sentence structure even if they don’t describe that structure using grammatical terms. This chapter’s Closing Worksheet asks readers to find out how people typically use the terms for key concepts in their demonstrations. For example, what does "sentence" mean to many people?