Thanks for the suggestion. Point 1 interest class, already done. But the smaller one always insist to be accompanied by the elder one. So what they are learning are both together. Otherwise, the smaller one will not go. Point 2, planning to do when they grow bigger.
May daughter is 3 yrs old and I encouraged her to speak in front of people answering questions. Eventually she did it after 15 mins encouragement then I gave her a piece of chocolate. She was so pround and said it was a reward from my mom to the other kids. From that point, she started to be more and more open. I think the point is parent's "CONTINUOUS" acknowledgement and spiritual support, encourage kids to be brave to try, result is another matter.