Hello Bindusriram,
I had the opportunity to attend many sessions on Group Discussion in my school and college life. From what I have learned, I can suggest that there should be a systematic approach to G.D. Firstly, there should not be more than 8-10 students in a group. Out of these, you can select one team member to be the group leader. Give a simple topic and ask them to communicate in English only. Initially, it may be a bit challenging, but gradually, they will gain confidence. Ask each group member to present points in favor or against the topic. Then, the group leader will jot down all the points and summarize the conclusion to all other group members. You can rotate the group leader periodically. The main focus of G.D. should be on discussion rather than argumentation.
For interviews, conduct mock interviews and encourage them to speak. I believe that unless they gain the confidence to express themselves, it will not be beneficial. Ask them to talk about themselves, their hobbies, etc.
I hope this guidance is helpful.
Thanks,
Pratik Raj