Using Balacheff's (2013) model of conceptions we analyzed textbook examples in two sections that modeled the mathematical work needed to answer two reading questions and used the intended conceptions to identify control structures in student responses to those questions. Reading questions are an interactive textbook feature meant to entice students to read the textbook before attending the lesson when such ideas will be discussed; as students provide responses in their interactive textbook, the instructors can learn about how students are thinking about the content before a lesson. We found additional control structures, which suggest additional conceptions beyond the ones promoted in the textbook. We discuss implications for designing these types of questions in interactive textbooks.