Celebrate the effort
A language can only be learned by using it. If learners are making mistakes, it means that they are trying and practicing new skills. Encourage and celebrate the effort.
Practice and model self-advocacy for understanding
I introduce these four phrases very early in the year, and we practice them at the beginning of every subsequent class:
Can you repeat that?
Slower please.
I don't understand.
I don't know.
Use these phrases yourself when you don't understand what a learner is staying; this models the behavior for the learners. Praise learners every time they use one of these phrases -- it means that they are self-advocating for understanding.
Correct errors selectively and thoughtfully
Error correction in adult beginning English learning situations is an art form. Too much or too-public correction can stifle learners' willingness to make mistakes. Too little correction can allow errors to fossilize.
Here are some things to consider when deciding whether and when to correct an error:
Is the error directly related to the primary focus of the lesson? If yes, then definitely correct it. If you’re doing an accuracy exercise (like very controlled practice), correct it right away. If you’re doing fluency practice (encouraging the learners to speak more freely in less-controlled practice), then consider addressing a sampling of the errors at the end of the exercise, to avoid interrupting the fluency practice.
Does the error impede intelligibility/understanding? If not and it’s not directly related to the lesson topic, then let it go (but note it to possibly address in a later lesson).
Is the error being made frequently? Then consider addressing it in a future lesson.
What is the likelihood of success? Is the learner ready for the correction or is the language level too advanced? Is this a time in the lesson that the learner will be receptive to the correction?
Unless the error was directly related to the primary focus of the lesson and occurred during an accuracy exercise, it's often best to delay the correction. Note the errors, then when the learners have completed the exercise, repeat a few of the errors and see if the learners (as a group) can identify and correct the error. Also consider addressing the errors as part of a lesson in the near future.
For more error correction information and practice, here's a self-paced minicourse on error correction with adult beginning English learners.