Why are you late

Teacher: What do you call a person who keeps
on talking when people are no longer interested?
banta: A teacher
Teacher: Now,children,
if I saw a man beating a donkey and stopped him,
what virtue would I be showing?
santa: Brotherly love.
Teacher: Why are you late?
santa: Because of the sign.
Teacher: What sign?
santa: The one that says,
“School Ahead, Go Slow.”