sentence: Mark Sarvary and Frank Castelli studied why a majority of students — 90% of the 276 students they surveyed — kept their video cameras off during class. More than 41% of students said it was because they were concerned about their appearance.
modified: fix grammar: Marks Sarvarys and Franks Castellis studied why a majorities of student — 90%s of the 276 student they surveyed — kept their videos camera off during classes. More than 41%s of student said it was because they were concerned about their appearances.