Welcome to Science Buddies!
It looks like you're planning on doing a social science experiment.
To carry out this project, you will need several groups to complete the task.
For example, each person listening to R & B and classical music. On the other hand, the control group will not be listening to any music.
You might want to select your music genres as different as possible. For example, heavy metal vs. classical music because they consists of almost opposite assumptions.
I also recommend you to select songs almost equal length to the other genre.
You should select a concentration task ( a word search, a type of memory game, short passage/ answering questions etc.) that will be same for everyone.
After selecting a group of students (try to keep it in the same age group/ grade for reliable test measures), randomly assign each person a type of music ( each group should have the same number of people). Make sure you test the control group also! After experimenting, calculate the concentration task and take the average of each group. If you want to be statistically accurate, you can calculate an ANOVA (Analysis of Variance).
For 9th grade, I recommend you to check out this link http://www.sciencebuddies.org/science-f ... deas.shtml
, and start from choosing your topic of interest.
Hope this helps and good luck!