Sheltered instruction is an approach to teaching English language learners which integrates language and content instruction. The phrase 'sheltered instruction,' original concept, and underlying theory of comprehensible input are all credited to Stephen Krashen. Sheltered instruction is an approach to teaching English language learners which integrates language and content instruction. The phrase 'sheltered instruction,' original concept, and underlying theory of comprehensible input are all credited to Stephen Krashen.