The ''Treasures in the Sea: Use and Abuse'' unit that deals with authentic socioscientific issues related to the Mediterranean was developed as part of a national effort to increase scientific literacy. The unit aimed to enhance active participation of the learners and encourage higher order thinking in class by applying teaching methods that reduce the unfamiliarity felt by students. This was expected through an explicit use of a variety of teaching and assessment-for-learning methods, suitable for Science for All students. Our main goal was to examine the culture of Science for All classes in which the unit was enacted. In order to address the main learning objectives, we monitored students' performances in tasks that required the higher order thinking skills of argumentation and value judgment, which are central constituents of decision-making processes. We show that while socioscientific issues were discussed in whole class and small group sessions, and students' argumentation improved, there is still a long way to go in applying a thinking culture in non-science major classes. We suggest that science teachers should shift from traditional content-based and valuefree approach, to a sociocultural approach that views science as a community practice and the students as active participants in decision-making processes.