<p dir="ltr">This is a case study of Open Research in practice, part of a collection curated by The Office for Open Research, DOI <a href="https://doi.org/10.48420/c.8037148" rel="noreferrer" target="_blank">10.48420/c.8037148</a>. This study investigates how school-age children grasp the comparative concepts “bigger” and “smaller,” using behavioural tasks and preregistered Open Research methods to explore the link between language development and conceptual understanding.</p>