It is a pre-reading (and post-reading) activity where you have students activate prior knowledge before reading a text, and engage with some themes and issues they will deal with in the reading (which builds anticipation)
Using generalizations students will agree or disagree with statements before they read the book, and discuss reasoning with groups or the class. After they read the book, their opinions may change, based on what they read or learn. As a class or in small groups students can revisit the anticipation chart to explore any changes they may have.
Beers explains that the point is not to change the students' minds, but to encourage them to think deeply about their beliefs. Good anticipation guide statements should provoke thought and discussion amongst students. In her example, the students reading a sample guide called the statements "tough" because it was hard to know what contexts in which the statement was agreeable or not. They responded to a lot of the statements by saying, "It depends." That's what you want to hear! It's not about right or wrong answers; it's about students beliefs and their explanations for them.
Beers recommends using words like "always," "never" and other nonnegotiable words in your statements. Play on students' usual line of thinking.
Here are some charts already done for you to use or gain ideas from:
What I really love about this activity is that you can adapt it to any piece of reading, any age level and it provokes deep discussion and thought.