The speaker is a blind student who is tired of being treated as if they weren't really there. A boy talks about them while they sit right across the table, as though they were a "decoy," not a person. He stares at them like a strange object, then acts puzzled when they feel uncomfortable. In class, he kicks their chair and wonders why they ask him to stop.
The refrain "I may be blind / But I am not dumb" returns three times, and each time it sounds a little more worn out. The speaker is not shouting. Instead, the tone is dry and sarcastic, seen in lines like "He must not have gotten / The memo." The sarcasm lets the speaker point out how clueless the boy is without losing their dignity.
The mood is frustrated and pointed, but also controlled. The poem's message is simple and clear: not seeing is not the same as not understanding, and the speaker deserves basic respect.