Sidney Poitier did not receive an Oscar nomination for portraying Gregory Miller in Blackboard Jungle.
Sidney Poitier plays one of Dadier's students even though Poitier had been playing adult characters before this film. Poitier was indeed much older than his character, but he and Vic Morrow, as one of the other students, are surprisingly believable despite their age. Poitier and Morrow don't really look younger than they really, but it is rather the way in which they portray their parts. They both convey in their physical manner the right sense of irresponsibility and immaturity. They bring the right type of slouching posture really that always reinforces their casual ways toward life, and the whole idea that they just don't seem to really care about much of anything.
Poitier's Gregory Miller is a troubled teen but not a bad one. He does not really have a lot of respect for adults as shown in his attitude toward Dadier for most of the film, but he is not a criminal like Artie West played by Morrow. Poitier is very good in playing indignation and he does it well here when Miller has quite the bad attitude in regards to Dadier. Poitier brings a calm and cool smugness to Miller, especially when he refers to Dadier as "chief" in a derogatory fashion. Poitier treads carefully not to go too far with Miller's treatment of Dadier. Poitier gets across the disrespect of a teenager and shows that he does not care much for Dadier, but properly stops short of hating him.
It is revealed that Miller is a decent enough guy really as the film progresses, but the film does not really stop to show this transition. The film pretty much leaves it up just to Poitier's performance to turn Miller from Dadier's enemy to his ally by the last scene of the film. Poitier is one actor who can do a whole lot with very little and he is able to do that here through his considerable natural charm. Poitier brings out his charm more fully as the film progresses and Miller begins to respect Dadier, and makes an effective transition by the end. Poitier makes it work by having not overplayed Miller's negative qualities at the beginning, but still keeping just the right edge to him even by the end.
The only problem with Poitier's work here are the limitations set upon him. I would have really liked to have seen more scenes involving Miller, and less of the melodramatic ones that involved Dadier's wife. It would have been more interesting for the film itself it did get into a little more detail with both Gregory Miller and Vic Morrow's character since their scenes tend to be the best in the film. Poitier never has quite enough material to turn this into a great supporting performance, but with what he does have Poitier gives a good one. Poitier makes his own impression throughout with his magnetic presence, and often out shines star Glenn Ford when they share the screen together.