1, you're welcome for the opening remarks. Basically, introduce yourself in which class first, and then introduce yourself from the topic. Remember to say "ごぁりがとぅござぃました" after the introduction.

2. After the teacher finished speaking, he thanked "ごぁりがとぅごぃますす". Then, of course, he answered according to their questions, and the specific content depends on the situation.