I sometimes draw a large S on the palm of my hand and when a student makes the mistake I just wave at them. They then self-correct.
You need to distinguish between 3 types of learners :
- beginners, who haven't fully internalised the rule yet. They need to keep hearing the correct form and "noticing" it until it's assimilated. Let them speak and then repeat the correct form, making sure they've noticed the correction.
- intermediates who know the correct form but, in the heat of the discussion are more concentrated on what they want to say than how they say it. At this level, they're overloaded -they can't yet focus on expressing meaning and on accurate form at the same time. In this case, take notes, put the mistakes up on the board and let them self correct after the activity.
- advanced students who have the error as a "fossilised" component of their language. They know the rule too, but in their spontaneous production continue to simplify. These are the ones I wave at, in the hope that the signal (they know exactly what it means) spurs them on to thinking about form and meaning at the same time.
So smile and wave, smile and wave - as they say in
Madagascar.