This study was developed by high school students and teachers on combining curricular theory and practice in the pedagogical teaching of science, as well as on practicing environmental education in a multidisciplinary way. Before starting sampling, professors and students were trained by an expert on this subject. Sampling were performed during seven months in two sandy beaches, Flecheiras and Emboaca, located in the northeast coast of Brazil. Each point had 60m x 20m transects (in triplicates) for manual collection of macroplastics from the superficial sediment. All collected plastic was separated by category, such as: PET bottles, bottle caps, straws, plastic bags, tires and “unidentified” (adapted from UNEP, 2016). Items were counted and weighed, and then plotted in a spreadsheet for further analysis and creation of a database. The total amount of litter was 4,214 items (71.55 kg) in Flecheiras, and 4,209 items (129.70 kg) in Emboaca. Despite the differences in weight, the number of items was similar between locations. We believe that high abundance of plastics in Emboaca is due the dynamics of marine currents, that brings a great contribution of waste to this region, as this place is out of the village; this distance also limits beach clean up by the municipality. There is a different situation in Flecheiras beach, as this beach is located by the village, and receives thousand of tourists annually; even with daily beach clean up in Flecheiras, the high amount of litter may be due the continuous disposal by beach users (mainly tourists), and also urban drainage. Identifying sources is essential for creating science-based strategies to prevent the entry of plastic waste in costal zones, and the results and hypotheses formulated in this study are being used to create an oficial document to the municipal council of Trairi city (where these beachs belong).