Too easy, kid's bored → jump a level within the same curriculum, don't change publishers.
Too hard, kid melts down → drop a level or switch to a spiral-based program (Saxon, Math Mammoth) that reviews concepts continuously.
Format mismatch (visual vs textbook vs video) → same publisher, different format, if available.
Wrong pedagogy fit → THEN change publisher. This is the rare, hard swap.
- Symptom: kid finishes in 10 min → level up.
- Symptom: tears, refusal, physical stalling → drop a level.
- Symptom: "I get it in the video but not on paper" → change format.
- Symptom: "None of this makes sense to me" (parent) → change publisher.