Producción Científica This paper presents SLEek, an ontology for the context-aware recommendation of learning activities in Smart Learning Environments (SLEs). SLEek creates an actor-artifact network that is especially suitable for the context-aware recommendation of activities across spaces in formal and informal contexts. SLEek implementation reuses vocabularies from the Web of Data and is currently used in a dataset of 17K learning activities. Junta de Castilla y León (grant VA257P18) Fondo Europeo de Desarrollo Regional - Agencia Estatal de Investigación (project TIN2017-85179-C3-2-R)