In The Absolutely True Diary of a Part-Time Indian, what are two examples of Junior (Arnold) being discriminated within the first 150 pages of the book?
There are plenty of examples in the first 150 pages of discrimination against Arnold. Firstly, you might like to consider the way that Rowdy responds to Arnold when he tells him that he is going to the school at Reardan. Rowdy first insults him, calling Arnold a "retarded fag" before finally going on to hitting Arnold in the nose so that his nose "bled like a firework." Arnold discovers that his desire to study at a school where he can gain a proper education means that he is discriminated against by his own people.
For another example of discrimination, but this time coming from whites, consider how Arnold is treated by his new classmates at his new school on his first day and how they stare at him:
They stared at me, the Indian boy with the black eye and a swollen nose, my going-away gifts from Rowdy. Those white kids couldn't believe their eyes. They stared at me like I was Bigfoot or a UFO. What was I doing at Reardan, whose mascot was an Indian, thereby making me the only other Indian in town?
Arnold is shown therefore to be trapped between a rock and a hard place. He is discriminated against by his own people because of the way in which he feels better than them. He is also discriminated against by the whites at his new school because he is not one of them and is an Indian.