I just used screen time and obesity in my intro psych class as an example of correlational research. Cause and effect can be tricky.
Today the NY Times has a piece on screen time and the type of content that is viewed. The summary seems to be that as elementary-aged children spend more time viewing television, a lower proportion of the time involves “educationally beneficial” content. Perhaps an important related question is how much “educational content” is available. Still, if the proportion shifts because there are few productive options, parents should know that this is the case.