Acquisition of a second language develops on a continuum from Basic Interpersonal Communication Skills (BICS) to Cognitive Academic Language Proficiency (CALP) (Cummins, 1994). BICS involves development of social, conversational language competence for oral communication. ESL learners can comprehend social language through their observations of non-verbal behaviours (e.g. facial expressions, gestures), reactions from others (e.g. shocked, surprised, pleased), voice cues (e.g. intonations, phrasing, stress) and other contextual cues. ESL learners need a minimum of two years of ESL education to develop BICS.
CALP on the other hand, involves mastery of cognitively challenging, grade appropriate learning tasks aligned with the program of studies. ESL learners at this level of competency no longer require non-verbal cues and intensive face to face interaction. Instead, they are able to understand abstract academic language and to meet the literacy demands of subject content. Acquisition of CALP is a long, uneven and gradual process that may require varying types of ESL programmatic support over the entire K-12 experience of a child (Collier, 1995; Roessingh & Kover, 2003). The following figure presents the complexities involved in the second language acquisition process.
