It's polite to clap for others' performances.
Jill's classmate is performing a dance for the class that ends with a flourish.
Jill wants to react to her classmate's performance.
Jill joins the class in a round of applause for the dancer.
Jill just stares at her classmate blankly as the rest of the class claps in appreciation.
Jill's classmate is happy that the whole class showed their support for her performance.
Jill's classmate thinks Jill is mean for not showing any appreciation for their dancing.