* He was expecting a challenge: Maybe Igor is a really good speller and finds spelling tests too easy. He might be unhappy because he didn't get to test his skills on something harder.
* He didn't get the grade he wanted: Perhaps Igor was hoping for a perfect score, but he made a small error that he didn't realize. Even a tiny mistake could make him feel disappointed.
* He thinks he cheated: Maybe Igor was feeling insecure about his spelling skills and secretly looked up the answers. Even though he got everything right, he might feel guilty and unhappy.
* He's unhappy for another reason: Sometimes people are unhappy for reasons that have nothing to do with a spelling test. Maybe he had a fight with a friend or is worried about something else.
Let me know if you'd like to try and figure out the real reason!