A time for telling

Suggestions for improving text understanding often prescribe activating prior knowledge, a prescription that may be problematic if students do not have the relevant prior knowledge to begin with. In this article, we describe research about a method for developing prior knowledge that prepares students to learn from a text or lecture. We propose prior knowledge that prepares students to learn from a text or lecture. We propose that analyzing contrasting cases can help learners generate the differentiated knowledge structures that enable them to understand a text deeply. Noticing the distinctions between contrasting cases creates a "time for telling"; learners are prepared to be told the significance of the distinctions they have discovered. In 3 classroom studies, college students analyzed contrasting cases that consisted of simplified experimental designs and data from classic psychology experiments. They then received a lecture or text on the psychological phenomena highlighted in the experiments. Approximately 1 week later, the students predicted outcomes for a hypothetical experiment that could be interpreted in light of the concepts they studied. Generating the distinctions between contrasting cases and then reading a text or hearing a lecture led to more accurate predictions than the control treatments of (a) reading about the distinctions between the cases and hearing a lecture, (b) summarizing a relevant text and hearing a lecture, and (c) analyzing the contrasting cases twice without receiving a lecture. We argue that analyzing the contrasting cases increased students' abilities to discern specific features that differentiated classes of psychological phenomena, much as a botanist can distinguish subspecies of a given flower. This differentiated knowledge prepared the students to understand deeply an explanation of the relevant psychological principles when it was presented to them. These results can inform constructivist models of instruction as they apply to classroom activities and learning from verbal materials. In particular, the results indicate that there is a place for lectures and readings in the classroom if students have sufficiently differentiated domain knowledge to use the expository materials in a generative manner.