The SIOP® Model is the only scientifically-validated model of sheltered instruction
The SIOP® Model is a research-based observation instrument that has been shown to be a valid and reliable measure of sheltered instruction (Guarino, Echevarria, Short, Schick, Forbes, & Rueda, 2001). SIOP is also used as a model for lesson planning and implementation of high quality sheltered instruction. In a study examining the effects of the SIOP Model on student achievement, students whose teachers implemented the SIOP model to a high degree in middle school classes outperformed those students in sheltered classes whose teachers were unfamiliar with the model.
