Age-Gradient Entry Criteria for a Single-Entry K-12 Competitive Python Textbook: A Placement Framework for Heterogeneous Vietnamese Learners

A Vietnamese K-12 Python curriculum that targets learners from Grade 5 through Grade 12 at a single textbook entry point faces a structural placement problem: a sevenyear age span subsumes wide variation in reading fluency, mathematical maturity, and prior programming exposure. This paper develops an entry-criteria framework for Volume 1 of a proposed "Python Pathway" textbook series, positioning placement along four operational dimensions — Vietnamese reading fluency, mathematics maturity, prior computer-science exposure, and age-linked attention and metacognitive factors. Drawing on established placement-diagnostic research (Tew-Guzdial FCS1, McCracken multi-institutional study), reading fluency research (DIBELS, Vietnamese 2018 General Education Program textcomplexity bands), mathematical prerequisites for algorithmic thinking (Papert pre-programming primitives, Pea & Kurland LOGO findings), and the Vygotsky-Bloom prerequisite-andmastery tradition, we propose a diagnostic rubric with four components and a routing decision tree that maps the fourdimensional profile to one of six placements: reading remediation, mathematics remediation, Vol 0 (pre-code volume), Vol 1 standard entry, Vol 1 skip-ahead, or Vol 2+ direct entry. The framework surfaces three textbook design implications: a "quick path" callout for experienced older learners, Grade 6–7 prose complexity as the exposition target, and explicit Scratch-habit interference handling in the variable-assignment chapter. The framework is advisory pending empirical calibration of traceitem thresholds and Vietnamese-specific reading fluency norms, both flagged as open questions.