Mobile assisted language learning (MALL) has developed and gained importance over the years in foreign language learning settings. However, mobile phones are still perceived as distracting devices in most of the schools. Within the field of second and foreign language learning, one of the most difficult things for school teachers is to give feedback to students when using a mobile device. In the present paper we present a case study research, which will investigate the best form of giving feedback via WhatsApp to students in primary education. Mobile instant messaging (MIM) has been used to practice vocabulary as well as the speaking and listening skills, but the study focuses on the feedback that the students have received. 30 primary (volunteer) students were selected to participate in the 3-week study and were divided into 3 groups, according to their age (low, middle and upper primary). A mixed approach method was employed to analyze the data (quantitative and qualitative). Results indicated that the most popular form of feedback among young students were smileys and images and not written feedback, and the study reveals that a set of varied images, even to send corrective feedback was an engaging element for the young students. Upper-primary students considered the written feedback more interesting, since they received more language-related details with this type of feedback than with a simple image.