The importance of mathematical concept development and language is recognized early in children's schooling as they mature through shape and counting experiences. The reader may recall instances of a youngster referring to a “corner” of a shape before the reader has the language of vertex. This language precision needs to continue to grow as the learner moves through arithmetic into algebra, geometry, and further mathematics. This precision is essential and is reinforced in the common core standards for mathematics (2010). If the primary goal is to facilitate proficiency in math for all students (including students with disabilities), there needs to be an emphasis on the deeper conceptual development and the uniquely precise nature of mathematics language both at the pre-service and in-service levels. This is essential as literature suggests that there is a significant relationship between teachers' mathematical knowledge and student achievement. The lack of teachers' mathematical knowledge prevents explicit instruction in the area of math concepts and/or a lack of focus on the mathematical language. This in turn causes barriers for k-12 students as they advance in the math curriculum. In this paper, the authors will discuss (a) the importance of mathematical concept development and language; (b) provide an example of a lack of precise conceptual understanding of prime number among pre-service teacher math educators; and (c) list explicit strategies that can be used to facilitate both the conceptual and language development at the pre-service level.