Investigating strength of relationship

[Boogeyman]

I was assigned a project in Applied Math and I chose to investigate the strength of the relationship between Math and Physics. My scope of tests is still limited, so I decided to first do a chi squared test (to show independence) and then determine the product moment correlation coefficient. Problem is the chi squared suggested independence, but my pmcc turned out to be 0.69. So I checked these two conflicting tests and my teacher did them but we haven't come up with anything else.

Is there any way this could be possible. If anyone wants to see my data (it's really not much) I will gladly upload it.

 

[Boogeyman]

By the way the correlation coefficient gives the relationship between the two...it ranges from -1 to 1. So imo 0.69 is pretty strong positive relationship. But this contradicts the independence suggested by the chi squared..