The district board of education shall develop a plan for in-service training for bilingual, ESL, and mainstream teachers; administrators who supervise bilingual/ESL programs; and administrators and any personnel who observe and evaluate teachers of Multilingual Learners (MLs). The plan shall include instructional strategies and appropriate assessments to help MLs meet the NJSLS and the WIDA English language development standards. All bilingual and ESL teachers shall receive training in the use of the ESL curriculum.