This paper focuses on the role of language and some issues associated with identifying appropriate language of instruction for three foundational Maths ideas in the Early Years of schooling. These are considered in relation to the project: "Strong Literacy and Numeracy in Communities--Numeracy Component." This had two broad goals, firstly to work with paraprofessional Indigenous teachers to determine an effective language of instruction for specific foundational numeracy concepts and secondly, to create a resource to enable this to be shared. Only two of the project sites are considered here. Both are in Yolnu communities in northeast Arnhem Land, where English is not widely used for interaction. We focus on the use of first language, Djambarrpuynu, for the children's concept development. The English language that can be used is determined by what is possible for early second language learners. We will share some samples of the Djambarrpuynu identified for teaching early number ideas. We will describe the process by which suitable expressions for the key ideas in Djambarrpuynu were identified and some issues that arose regarding the use of language for comparing numbers. The project showed how "Maths" lessons are a time both for concept development and for language development.