The primary purpose of this study is to look into the effectiveness of Sheltered Instruction Observation Protocol (SIOP) model in a Pre-K classroom with ELLs. The participants of the study were 12 students with different cultural and linguistic backgrounds in a Pre-K classroom with English language learners. To measure the effectiveness of the SIOP model in the classroom, data were gathered using the students’ work samples and classroom observation reports, as well as answers from the parent questionnaire interview. Results showed that after using the SIOP model in the classroom there was an increase in students’ basic language skills, which includes, writing, speaking, listening and reading. The results of the study also revealed that reading out loud, hands-on activities, modelling, scaffolding, using visuals in the classroom, considering students’ prior knowledge and students’ strengths in creating classroom lesson plans and activities are effective teaching strategies for ELLs.