In teaching Vietnamese to foreigners, there are various methods used to increase the efficiency and help learners access Vietnamese easily. The application of corpora in teaching is one of the useful and practical methods, as it increases the acquisition and usage of non-native languages. However, in Vietnam, this method still faces numerous limitations due to the lack of suitable corpora that meet the needs of teaching and learning Vietnamese. In this paper, we discuss the procedure of building a Vietnamese corpus, sampling, collecting, and processing materials. This corpus is used to construct vocabulary sets appropriate for each grade level and extract examples of vocabulary usage for each real-world context.