Read the【Case Reflection】in this section and think about the questions:

Mr B has a speaking class for grade one students in a junior school. First, he selects a dialogue with three characters, and divides all the students into groups of three. Then he asks each student in the group to select a role to practise the dialogue. Finally, the groups act it out for the whole class.

Please identify the merits and shortcomings in the above speaking class, and make suggestions for further improvement.