The Natural Approach developed by Stephen Krashen and Tracy Terrell believes that adults can still acquire a second language naturally like children through comprehensible input. It focuses on providing a low-anxiety environment where adults acquire, not learn, the language through activities like role-plays, songs, and games. The teacher acts as a facilitator and students progress at their own pace through the natural order of language acquisition without explicit grammar instruction. While easy to implement, it may take a long time for students to develop more advanced skills under this approach.