One potential means to develop students' contextual and conceptual understanding of mathematics is through Inquiry Learning. However, introducing a problem context can distract from mathematical content. Incorporating argumentation practices into Inquiry may address this through providing a stronger reliance on mathematical evidence and reasoning. This paper presents a framework derived from the implementation of multiple, successive Argument-Based Inquiry units to 8-10 year olds. Three key knowledge domains are identified: mathematical, contextual and argumentation knowledge. Key components and roles of each domain are addressed and offered as an initial framework for further research.