If a learner does not achieve the expected performance, what type of testing…

Assessment in the teaching-learning process is classified by its PURPOSE and TIMING. Formative assessment is carried out continuously while instruction is underway, to monitor ongoing progress and let a teacher adjust the lesson in real time. Summative assessment is carried out at the close of a unit, term, or course, to certify the overall level of achievement reached. Diagnostic assessment is carried out specifically to pinpoint the underlying cause of a learner's persistent difficulty or shortfall — probing prior knowledge, misconceptions, or skill gaps before any corrective step is planned. Remedial teaching is the corrective instructional response — reteaching, extra practice, alternate methods — delivered once a cause has already been identified; it is a teaching action, not a testing step.

Here the learner has already fallen short of the expected performance, and the question asks specifically for the testing done to find out the reason behind that shortfall. By definition, isolating the cause of a learning gap before deciding on a remedy is exactly the purpose of diagnostic testing, so diagnostic testing is what gets administered at this stage.

• Formative testing tracks progress at regular intervals across a unit; its role is continuous monitoring during learning, not investigating why one specific outcome was missed.

• Remedial teaching is the follow-up instruction delivered after a cause is already known; it is the corrective action itself, not the testing step used to discover that cause.

• Summative testing is administered at the end of a unit, term, or course as a final exam or end-of-term test to certify overall achievement, not to probe an individual performance gap mid-course.