Language Concepts and Language Acquisition
Know the building blocks first
Domain I rewards precise vocabulary more than name-dropping theorists. Know the five subsystems: phonology (sound system, including phonemes absent from the student's L1), morphology (smallest meaning units; free vs. bound morphemes), syntax (word order and sentence structure), semantics (word meaning), and pragmatics (language in social context - register, politeness, sarcasm). A student who decodes fluently but misses an idiom or a joke is a pragmatics item.
Acquisition theory that shows up on items
Krashen's five hypotheses anchor most questions: acquisition vs. learning (subconscious vs. conscious rule study), natural order, the monitor (editing requires time and explicit rule knowledge), comprehensible input (i + 1), and the affective filter (anxiety, low motivation, low confidence block intake). Cummins supplies BICS (conversational fluency, roughly two years) versus CALP (academic language, five to seven years) - the explanation for a student who chats easily at lunch yet fails a science reading. Vygotsky's zone of proximal development and scaffolding, plus Canale and Swain's communicative competence (grammatical, sociolinguistic, discourse, strategic), typically appear as distractors.
The traps
Developmental errors are not interference. "She goed" is overgeneralization of the regular past-tense rule - evidence the learner has internalized a rule - not transfer from Spanish. Silence in a pre-production stage is normal, not defiance. Reject items claiming older learners always win long-term or that bilingualism causes confusion.
Rule of thumb
When an item describes a learner error, ask: does the pattern come from the L1 (transfer), from the target language's own rules (overgeneralization), or from a developmental stage (silence, formulaic chunks)?