Cooking potatoes

This task is about fair testing.
Neil set up the following experiment to find ways to speed up the cooking of a potato.
cooking potatoes experiment setup

Question 2Change answer

a)  Carefully explain two reasons why this is not a "fair test".
1.
2.

Question 2Change answer

b)  What two variables have been controlled for this experiment?
1. 
2. 

Question 2Change answer

c)  Neil re did this experiment and made it a "fair test".
What should Neil measure so he knows which potato cooks the fastest, and how could he do this?
Measure: 
How: