Educational data science is an emerging transdisciplinary field formed from an amalgamation of data science and elements of biological, psychological and neuroscientific knowledge about learning, or learning science. This article conceptualises educational data science as a biopolitical strategy focused on the evaluation and management of the corporeal, emotional and embrained lives of children. Such strategies are enacted through the development of new kinds of digitally-mediated "biopedagogies" of body optimisation, "psychopedagogies" of emotional maximisation, and "neuropedagogies" of brain empowerment. The data practices, scientific knowledges, digital devices and pedagogies that constitute educational data science produce new systems of knowledge about the child that are consequential to their formation as "biodigital" subjects, whose assumed qualities and capacities are defined through expert practices of biosensing, emotion analytics, and neurocomputation, combined with associated scientific knowledges. The article develops the concept of transcoding to account for the processes involved in the formation of the biodigital child.