To what extent would it be observable to see a difference in time period of simple pendulum with different angles?

I am a high school student that has attempted carrying out the simple pendulum experiment for angles between 10,20,30,40,50 degrees and realized from the result that there is a 0.01 s difference between each angle so therefore is the information I am getting is true? Also if possible, I am not very good in math in other words I don’t know what partial differentiation because we don’t study this in school but fine with basics of integrations and differentiation, in other words would there be a lot of math explored or can I talk about the physics behind it only?

Thank you very much because I have no clue if I should stick with this topic to do a report.