Children with specific language impairment (SLI) frequently experience difficulties with understanding vocabulary and are subsequently academically disadvantaged. This study describes a curriculum-based assessment and therapy technique and its implementation with two children with language difficulties. Mathematical vocabulary that the children did not understand was randomly allocated to either the treatment or the control conditions. Over a period of seven to eight weeks, two boys were individually taught 18 words each. Each word was taught in one session only. The intervention was found to be effective for both children. The results of this study have implications for the rate of teaching of receptive vocabulary, the role of speech and language therapy in schools and the assessment of receptive vocabulary.