During a lesson the learner mounts the pavement while turning left. What should the instructor's immediate and follow-up actions be?

1. Say nothing to avoid upsetting the learner, then mention it next week
2. Shout at the learner so the lesson is remembered
3. Stop the lesson permanently and report the learner to DRTS
4. Intervene immediately to regain safety, then when calm, analyse why it happened and practise the correct approach