Step 1: Setup
Step 2: Experimenting
Step 3: Calculations
Assume the index of refraction of air to be 1 or 1.003
Snell's Law: [index of refraction of air] * [sin(incidence angle)] = [INDEX OF REFRACTION OF MEDIUM] * [sin(refracted angle)]
Then calculate the mean of these index values.
Use this to determine the speed of light in the medium.
Formula: SPEED OF LIGHT IN MEDIUM = speed of light in vacuum/index of refraction of medium
And congrats! Your done!