"...be careful not to make a habit out of talking to students too loudly, clearly, or slowly, as they will get used to this type of speech and struggle to understand authentic speech during interactions outside the class. Overall, it is recommended that you be as authentic (or natural) as possible when speaking and writing to your students so that they get the opportunity to receive authentic input."
- Krashen, Stephen D. 1982. Principles and practice in second language acquisition. Oxford: Pergamon.