The definitions in this section apply throughout this chapter unless the context clearly requires otherwise.
(1) "Eligible pupil" means any enrollee of the school district whose primary language is other than English and whose English language skills are sufficiently deficient or absent to impair learning.
(2) "Exited pupil" means a student previously enrolled in the transitional bilingual instruction program who is no longer eligible for the program based on his or her performance on an English proficiency assessment approved by the superintendent of public instruction.
(3) "Primary language" means the language most often used by the student for communication in his/her home.
(4) "Transitional bilingual instruction" means:
(a) A system of instruction which uses two languages, one of which is English, as a means of instruction to build upon and expand language skills to enable the pupil to achieve competency in English. Dual language education and tribal language education as defined in RCW
28A.300.577 are the preferred transitional bilingual instruction program models; or
(b) In those cases in which instruction in two languages is not practicable as established by the superintendent of public instruction and unless otherwise prohibited by law, an alternative system of instruction which may include English as a second language and is designed to enable the pupil to achieve competency in English.