Act 1,scene 3 why mr m cannot predict isabel's response as much as he can predict thami's

Isabel differs from both Mr. M and Thami in one very significant way: she is white. She also attends Camdeboo High School, which is not just an all-girl school, but also an all-white school. Isabel holds a high place in the dominant white culture yet has no problems mixing with blacks in the educational setting.