Pendulum Experiment - time period and length of string

[physics-chris]

Homework Statement

Hi, in class we done the classic pendulum experiment to investigate the relationship between time period and the length of the string. Here are my averages for time period and the length:
Length (m)----Average time (T1+T2/2)
0.2 11.3
0.4 14.9
0.6 17.41
0.8 19.98
1 23.71

The Attempt at a Solution

Having drawn the graph of Time against Length and getting a strong positive correlation, I was expecting time squared to produce a curved graph. However, it is coming out as a stretched "s" shape, all be it a very faint one, so it isn't far off from being straight. Should this be the case? And also, do I need both graphs together to demonstrate Time being proportional to Length, or, will either one be sufficient?

Thanks

 

[rock.freak667]

Try plotting T² vs l or T vs√l