When a number of students regularly fail in the exams, it can be understood that it is

When a number of students regularly fail, it points most directly to the teacher's failure.

Widespread failure in one class implicates the teaching, method and clarity rather than each learner alone.

Effective teaching is judged by learners reaching the intended outcomes, so mass failure signals ineffective teaching.

The system's failure is a broader factor that does not pinpoint the immediate classroom cause.

Blaming the textbooks isolates one input while ignoring how it is taught.

Attributing it to individual students cannot explain why so many fail together.