4. Quality of observations/data 

 Consistent data 
Distance increases with increasing concentration
and time.@ 
 Accurate measurements/observations 
Accurate measurement of the distance reached
by the diffusing KMnO4 in every five minutes.@ 
 Completed data table 
All data entered in the table. 
 Correct units 
Distances are labelled as mm. 
Qualitative description 
* (Variability of distance of diffusion within
a single cube might be mentioned 
5. Graph 

 Curve is appropriate to data trend 
Curve drawn best fits data points. 
 Points plotted accurately 
Plotted points are accurate. 
 Appropriate scale 
Values of scales are appropriate to ranges
of data. 
 Axes labelled with variables 
Time in minutes; concentration in percentages;
distance in mm. 
 Variables placed on correct axes 
Dependent variable, distance of diffusion
is the y axis; independent variables, time and concentration
(on the x axis) can be placed on separate graphs OR combined
as three separate plots of concentration within one graph
with time as the x axis 
6. Calculations 
Not required for this task 
 Calculated correctly 

 Substituted correctly into relationship 

 Relationship stated or implied 

 Units used correctly 

 Use all data available 

7. Conclusion 

 Consistent with scientific principle 
As concentration and time increase, distance
of diffusion also increases. 
 Sources of error 
* (Measurement of distance may be hard to
measure accurately.) 
 Consistent with data 
Consistent with student's experimental results.
1 
 Relationship among variables stated 
Distance of diffusion is related to concentration
of KMnO4 and/or time. 1 
 Variables stated in conclusion 
Distance of diffusion, concentration of KMnO4
solution, time. 