How do textbooks function differently across educational systems, and what happens when those systems operate in low-resource environments? Following on from previous episodes on the CBC open textbooks project in Kenya, Lucie Hazelgrove-Planel and David Stern discuss textbooks more generally. They discuss the different roles textbooks play in different educational contexts, and how a lack of contextualisation can block learning. They consider how an open textbook model, where they can be adapted into different variants without requiring an entirely new publication, could revolutionise the way textbooks are produced and used globally.