This is the 12551st most frequent Russian word.
комментариями
"Комментариями" means "comments" (instrumental plural form).
The word "комментариями" is used in the instrumental case, plural, indicating the means by which the students shared their opinions—through their comments.
Студенты делились своими комментариями о прочитанной статье.
The students shared their comments about the article they read.
Here "комментариями" is in the instrumental case, plural, describing the feedback as an instrument that brought satisfaction to the teacher.
Учитель остался доволен комментариями учеников после занятия.
The teacher was satisfied with the students' comments after the lesson.
In this example, "комментариями" in the plural instrumental case indicates the entities (comments) she is engaging with.