This research was aimed to: 1) know the effectiveness of formative evaluation using SOJA cards, 2) explain influencing factors in the implementation of formative evaluation using SOJA cards, and 3) identify the obstacles found during the implementation of formative evaluation using SOJA cards. This is an experiment research intended for a product try out whose result were explained in a research report. Quantitative approach was used in this research. The primary subjects of the research were grade 1 students. The data of research were collected by conducting interview, distributing questionnaire, and documentations. The data verivication was done by conducting member checking toward the informant, data gathering, data/ information checking. The data of this research was done inductively namely: data reduction and data display. The findings of the research show that: 1) formative evaluation using SOJA cards is really effective to prevent students from cheating, 2) the influencing factors of using SOJA cards 3) the obstacles found during the implementation of the formative evaluation using SOJA cards.