The document discusses the similarities and differences (S/D) learning strategy. It finds S/D to be the most effective strategy for increasing student achievement, generating a 45% increase. S/D works well because it allows students to build on prior knowledge, review material again when learning a second item, and creates strong memory bonds between items. The document provides a step-by-step process for implementing S/D, including gathering information, organizing it using tools like Venn diagrams, drawing conclusions through discussion, and applying the conclusions reached.