Personally, I think that it would be easier to go negative. With a five paragraph structure, it would be easy to do:
1)Intro, relevant example, state opinion
2)Relevant background, point 1,example of negative change, connect to opinion, transition
3)point 2, second example of negative change, connect to opinion, transition
4)concession to opposition (example of ways it has bettered society)
5)Summarize opinion and examples, validate opposition, strong finish
To be honest, I'd skew it in the way your professor is inclined to agree with. In my experience, it's a little easier to just agree with the person who will be grading the paper. If your professor is older and teaches through primarily lectures, I'd go negative. If your professor is young-ish to young and incorporates a ton of technology into the classroom, I'd go positive.
Positive would be really similar.
1)Intro, relevant example, state opinion
2)Relevant background, point 1, example of positive change, connect to opinion, transition
3)point 2, second example of positive change, connect to opinion, transistion
4)concession to opposition (examples of way it has negatively impacted society)
5)Summarize opinion and examples, validate opposition, strong finish
