Think-Pair-Share (TPS) activities in classrooms provide an opportunity for students to revise, practice and reproduce previously learned knowledge. Teachers also benefit from this active learning strategy by exploiting new learning materials, saving time by minimizing presentations and using it as a formative assessment tool. This article explores how a teacher can employ the strategy to both promote active learning and conduct formative assessment in a time-efficient way. To do this, a TPS activity was designed on an online platform along with an assessment rubric for student products. In 60 minutes, students thought individually on the topic provided, discussed and collaborated in groups and finally wrote down their paragraphs on the online tool. Each group shared paragraphs simultaneously. The teacher examined the paragraphs in terms of the predefined learning outcomes and determined the points to be revised. The students answered an open-ended online questionnaire a day later and the qualitative data were analyzed through a coding system. The assessment results successfully showed the learning points to be revisited and the results of the questionnaire supported the assessments of the teacher. The majority of the students revealed that they were satisfied and willing to do the activity again in the future.