Language is not 'soaked up.' The learner must understand the message that is conveyed. Comprehensible input is a hypothesis first proposed by Stephen Krashen. He purports that ELL's acquire language by hearing and understanding messages that are slightly above their current English language level." (Haynes, 2005) Although there are many ways to make input to second language students comprehensible, cooperative learning attends to many of the learning processes in second language acquisition in addition to the academic content students are responsible for learning. "When newcomers are assigned to a mainstream classroom and spend most of their day in this environment it is especially critical for them to receive comprehensible input from their teachers and classmates." (Haynes, 2005) The case for comprehensible input aside, there is also a need for comprehensible output. "According to research, learners need opportunities to practice language at their level of English language competency. This practice with English-speaking peers is called Comprehensible Output. Many researchers feel that comprehensible output is nearly as important as input." (Haynes, 2005) Teachers who create classroom environments that are collaborative and effectively implement cooperative learning strategies in lessons provide English language learners with many opportunities to receive comprehensible input as well as practice comprehensible output.