Research suggests teacher professional learning and collaboration are essential to support student achievement. However, our Middle Eastern and North African (MENA) English Language Learners (ELL) have lower academic achievement and our teachers are limited with professional learning inquiry cycle opportunities. Research also suggests vocabulary techniques that promote scientific discourse as a method to support Arabic speaking students. The convergent mixed methods descriptive case study, engaged in improvement science to better understand the disproportionate lower academic achievement for MENA ELL students. Two primary drivers were identified. First, the use of vocabulary techniques to support scientific discourse and second, the use of the Japanese lesson study (JLS) to engage in professional learning and teacher-led inquiry. One Plan, Do, Study, Act (PDSA) cycle occurred to enact the change ideas. Both quantitative and qualitative data were collected from students and teachers through pre/post inquiry cycle surveys, pre/post inquiry cycle vocabulary assessments, checklists, and reflections. Findings yielded several themes around teacher efficacy because of collaborative professional learning and increased averages for MENA ELL and non-MENA ELL student outcomes. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]