Ensemble characters for Matilda

Watch the video.

Tell me some of the ways the "ensemble" create character's.

Are they all the same?

Are there any differences in uniform?

How do they speak?

How do they interpret the words from the song?

What is the difference between the current students and the new students (Matilda and Lavender) ?

Considering the choreography, what does it add to this scene? What is the purpose of the movements within this song? What does it add to the characters of the ensemble?