A second-grade bilingual class has been studying geographic formations. They have been reading descriptions about canyons and caves, especially about those in their surrounding areas. Some of the reading material has been in Spanish, which has helped the emergent bilinguals (those in the process of developing either or both of their two languages) to grasp the important geographic concepts being taught. In English, the teacher has located reading materials at different levels of complexity for independent reading. As a class, they read challenging texts together, which then become the basis for conversations about the meanings encoded in the language used by the author. In this instance, the whole group conversation is about comparing and contrasting canyons and caves. The teacher asks a guiding question: What are the similarities and differences between caves and canyons?