The Comprehension Toolkit is a reading comprehension program for grades 3-6 with extensions to grade 8. It is based on 10 principles including fostering curiosity, collaborative learning, building instruction around real-world reading, and making thinking visible. The program includes 6 clusters focused on monitoring comprehension, activating prior knowledge, asking questions, inferring meaning, determining importance, and summarizing. It supports various instructional approaches including reading groups and content area instruction based on student needs.