To understand what teachers need to teach towards big ideas in the classroom, there is a need to systematically interface different conceptions of big ideas in mathematics with models of teacher knowledge. We conducted a literature review on horizon knowledge and big ideas to clarify both constructs and their relationships. Twenty-one journal articles were initially shortlisted, with within-case and cross-case analysis finally performed on four articles after inclusion/exclusion criteria. While it is clear that more work needs to be done, we tentatively conclude that to teach towards big ideas is to emphasise disciplinary ways of thinking that are empirically demonstrable to be fruitful for the learning of mathematics.