4. Quality of observations/data 

 Consistent data 
As angle i increases, angle r increases. 
 Accurate measurements, observations 
Angles of incidence and angles of refraction
measured to the nearest degree. Angles of r between 8 degrees
and 40 degrees. 
 Completed data table 
6 pairs of measurements with sine values. 
 Correct units 
Degrees for angle r; sin i and sin r are dimensionless. 
 Qualitative description 
* 
5. Graph 

 Curve is appropriate to data trend 
Graph of sin i vs sin r is a straight line (best
fit) 
 Points plotted accurately 
Points correspond to measured data. 
 Appropriate scale 
Sin i range (0.1  0.9); sin r range (0.1 
0.9). 
 Axes labelled with variabls 
Labels are placed on graph 
 Variables placed on correct axes 
Sin i on y; sin r on x 
6. Calculations 

 Calculated accurately 
Calculated accurately with appropriate use of
significant figures. 
 Substituted correctly into relationship 
Calculate slope as n= (delta sin i)/(delta sin
r). Points used should be on the best fit line. 
 Relationship stated or implied 
* 
 Units used correctly 
n is dimensionless 
 Use all data available 
Use the best fit line to calculate the slope
with chosen points on the straight line far from each other. 
7. Conclusion 

 Consistent with scientific principle 
Calculation consistent with index of refraction
taken from data provided. 
 Sources of error 
* 
 Consistent with data 
Conclusion is consistent with student's experimental
data. 
 Relationship among variables stated 
* 
 Variables stated in conclusion 
Index of refraction. 