What do the results mean?

Males worked best with hard rock music, followed by classical then no music. The females worked best with no music, followed by classical then hard rock music.
The average of both males and females, showed that no music had the best test results, followed by classical and then hard rock music.

Do they really show that?

The math calculations indicate the above is true.

Did they support my hypothesis, or is further work needed?

My hypothesis is rejected regarding classical music scoring better and the females would score higher than males. The classical music average fits in between the no music average and the hard rock music average. The males scored higher listening to hard rock and classical and it was only in the case of no music that the females scored better.

Are there other explanations for what happened?

The no music had the higher score, because most of the tests completed in school are done without music. When music is played it can be distracting, my results indicate this.
There was an even split of males and females.

How do my results compare to what I’ve read about this topic?

In looking at the test scores with both genders, the test with no music had the highest score.
On two occasions the males did better on the tests than females.

What could have been better about my method?

The tests were carried out on three consecutive days, if they were carried out over the span of two weeks, the students might not have remembered the types of questions (which were similar) and the results might have been different. Also, if the test marks had been recorded by the teacher of the class, the students might have tried harder on each test.