Kei te ārohi tēnei pepa ki te reo ote ako mā te huarahi o te reo Māori mai i te tirohanga Systemic Functional Linguistics (SFL). Ko te tino whakaaro o SFL he nui ngā rerekētanga o te reo whakamahia ai i te kura i ō te reo whakamahia ai i waho i te kura nā te mea he rerekē ngā horopaki reo.E ai ki ngā ariā SFL, ko te “rēhita”te hanga matua e whakamārama ana i taua rerekētanga. Kei ngā marau pērā i te pāngarau he “rēhita”motuhake tōna. Kua waihangatia te rēhita, ki ōna ake kupu, ki tōna ake takatoranga reo. A tōna wā ka tino whakararuraru ngāāhuatanga o te rēhita i te ako o ngāākonga.Kua whakaaturia e ngā rangahau te tino tikanga o te reo i te akoranga pāngarau me te tino mahi a te pouako hei whakatauira i te reo mō ngāākonga. Kei te ārohi tēnei pepa ka pēhea ngā pouako e ako ai i te rēhita me ngā rautaki ka whakamahia e ngā pouako hei ako i ngā kupu motuhake. This paper examines the language of learning and teaching in Māori medium schooling from the perspective of Systemic Functional Linguistics (SFL). Essentially SFL suggests that language use in school differs in important ways from language use outside the classroom. Because language situations differ, the primary construct in SFL theory for explaining linguistic variation is the “register”. Subjects such as mathematics are characterised by specialised registers. The register is made up of linguistic features that can pose difficulties for the learner. Research has highlighted the role of language in learning mathematics and the key role of teachers in modelling the register for learners. This paper examines how teachers learn the register, in particular the strategies teachers use in Māorimedium kura to learn the specialised terms.