Observing through the microscope was exciting because many of the students had never used a microscope before this year.
(Observing through the microscope; was; exciting; because many of the students had never used a microscope before this year) (many of the students; had never used; a microscope; T:before this year)
Observing through the microscope many of the students
was had never used
exciting because many of the students had never used a microscope before this year
a microscope T:before this year