The purpose of this study was to explore the effects of multi modal representations within writing to learn activities on students' critical thinking. Mixed method was used. The participants included 32 students 5th grade from elementary school. The groups were randomly selected as a control group and the other class was selected as the experimental group. Data collection tools has been Critical Thinking Test (CTT) and writing actives. The students were asked to tell their peers about the subjects in the unit with a writing activity using the summary writing type. The students performed three writing activities, one preparation and two real practice activities, in this process. The most basic dissimilarity between the groups is the request of the use of multimodal representations asked from the students in the experimental group. The Cronbach's alpha reliability coefficent of the CTT was determined as 0.72. The results of this study show that the use of the multi modal representations in writing to learn activities improved the scientific critical thinking of the students.