In this paper, we explored the primary students' after-class vocabulary behavioural learning patterns using a mobile user-generated-content (m-UGC) tool. A total number of 21 Grade 4 students from an elementary school in Hong Kong were recruited. Case study approach was adopted. Data collection included students' learning logs on the m-UGC tool. Content analysis and visualization were used to analyze data. Three sub-groups of primary students' after-class vocabulary behavioural learning patterns were identified and future studies were explored. Copyright © ICCE 2020 - 28th International Conference on Computers in Education, Proceedings. All rights reserved.