The expected level in a readback

In a fictional ground exercise, a controller has just assigned an original training aircraft a level of 7000 feet. The learner acting as the pilot reads back 9000 feet. The controller is concentrating on a second aircraft and acknowledges the call because the call sign is familiar. A recording later confirms the mismatch. No actual altitude instruction, operational frequency or aircraft movement occurs. The instructor asks the group to identify the information-processing failure and suggest a defense without diagnosing the controller or assuming malicious intent. The task supplies no universal phraseology script or jurisdiction-specific penalty. A useful response must compare what was issued with what was actually heard, identify the unresolved discrepancy and explain why confidence in a familiar call sign does not establish agreement on the level.