Author note — to cover

Take differences twice: a constant second difference is the signature of an n² term; contrast with constant first difference for linear and constant ratio for geometric. This page serves the Higher nth-term pipeline — sight recognition of quadratic sequences also appears, both tiers, on naming-a-sequence per A24. (A24, A25)

• Fluency — direct questions on spotting a quadratic sequence, limited to this lesson's stated scope (4 questions).
• Application — use the same skill in unfamiliar or contextual questions without introducing a later method (4 questions).
• Check — questions built around the exclusions and likely misconceptions named in the lesson brief (4 questions).