Development of the cardinality principle, an understanding that the last number-word recited in counting a collection of items specifies the number of items in that collection, is a critical milestone in developing a concept of number. Researchers in early number development have endeavored to theorize its development. Here we critique two widely…

How do classroom exchanges shape the developing forms and functions of literacy learning and teaching as students transition across the years of schooling? We explore this question using excerpts from literacy lessons from primary and secondary classrooms, showing how lesson exchanges develop as trajectories connecting different forms of 'knowing'…

Big ideas, sometimes referred to as key, core, fundamental or threshold concepts, are widely applicable concepts at the heart of disciplines that are or have been central and influential for their fields. Attention here is particularly directed to meta-concepts common to sister disciplines in the sciences. "Learning thresholds",…