"A primary school teacher was" joke

A primary school teacher was talking with her class.
Teacher: "Mary, what did you do at lunch?"
Mary: "I played with my doll, Miss."
Teacher: "Mary, If you can spell doll, you can go home early."
Mary: "D O L L"
Teacher: "Correct. Brian, what did you do at lunch?"
Brian: "I played with my ball, Miss."
Teacher: "Brain, If you can spell ball, you can go home early."
Brian: "B A L L"
Teacher: "Correct. Rangi, what did you do at lunch?"
Rangi: "I got hassled by all the other kids for being black, Miss."
Teacher: "That sounds like Racial Discrimination. Rangi, If you can spell
Racial Discrimination..."