Reducing large selections of text to their bare essentials: the gist, the key ideas, the main points that are worth noting and remembering. Supplemental Instruction is instruction that goes beyond that provided by the comprehensive core program because the core program does not provide enough instruction or practice in a key area to meet the needs of the students in a particular classroom or school. For example, teachers in a school may observe that their comprehensive core program does not provide enough instruction in vocabulary, or in phonics, to adequately meet the needs of the majority of their students. They could then select a supplemental program in these areas to strengthen the initial instruction and practice provided to all students.