Originally Posted by **Hero** A**What was the independent variable in this investigation? What was the dependent variable?**
Independent variable is the angle of incidence (because it is the one that can be varied).
Dependent variable is the angle of refraction (because it is dependent on the angle of incidence).
Have I got the independent and dependent variables mixed up? |

No, you are not mixed up - your answer is correct.

Originally Posted by **Hero** I'm concerned because I read somewhere that :
x-axis = independent variable
y-axis = dependent variable. |

Yes, that is usually how graphs are drawn (but not always).

Originally Posted by **Hero** But later in the question in the book it says: Draw a graph of sin i (y-axis) against sin r (x-axis). |

I think it asks you to do this because Snell's Law is equal to sin i/sin r, and so drawing the graph this way will result in a best-fit straight line whose slope is equal to the index of refraction.