Dancers

a.k.a. People likely to turn up at Terry's dance school (... I don't remember if it has a name)

Tappers
Terry Archer
Harriet Archer (though she quit)
Jess (Harriet's friend)
Marie Baxter (in Terry's class)
Brittany Morgan (usually paired with Terry)

Ballet Dancers
The Cahill triplets: Hilary, Nancy and Charity

Jazz
Jess (Harriet's friend)

Salsa
Jess (Harriet's friend)

Teachers
Miss Mary Anne