The rule layer resolves what it can, for free.
Every step of a student's step-by-step working is checked against the mark scheme's expected forms and a comprehensive library of known error patterns. When an answer matches, the classification is immediate, entirely deterministic, and costless, requiring zero model calls.
Teacher-inspectable rules
Every rule-resolved classification links directly back to a specific, readable criterion that an educator or auditor can inspect, avoiding black-box ambiguity.
Instant resolution
Known pattern transformations execute directly in memory. Clear structural errors and textbook steps are resolved instantaneously.
Escalation on ambiguity
Only student responses that cannot be confidently verified by deterministic criteria or proven error signatures route upward to model escalation.
Justification: Exact match against expected expansion form. Method condition verified.
Justification: Correct operational sequence applied; procedural arithmetic slip (32 – 12 recorded as 24 instead of 20).
Justification: Accurate downstream division based on previous working. Follow-through criterion met.
Complex formulations or anomalous reasoning that bypass standard rule conditions are passed into high-precision model evaluation.
Continue to Model Escalation