In the screenshot below, Greg identifies the 6th sentence as the main idea since the sentence contains the “author’s opinion” as quoted in the lecture. Instead of the 6th sentence, shouldn’t the last sentence from the passage be the main idea?
My thought process:
The 6th sentence conveys a possible reason/explanation of the controversy setup in the 3rd, 4th and 5th sentences. The last sentence which states “Indeed, the term pillow is probably a misnomer”, in my opinion, would be a “stronger” opinion as it directly challenges the nomenclature of “pillow lava”
I think everything after the 6th sentence is the author explaining his or her point / making a suggestion for a solution.
“Main idea” is a squishy term that the GRE doesn’t use anymore. A more useful term is “primary purpose”.