Incorporating design in science programs has been shown to enhance science understanding, practices, and problem-solving skills. However, instructors and students typically struggle with fostering effective communication within a design-based course. With better communication scaffolding, students would learn more content and also become better at communicating ideas, both of which are important learning outcomes. We have developed the Design-Based Science Plus (DBSP[superscript +]) idea communication framework that adds two communication scaffolding tools to design-based instruction. This framework supports students to have productive conversations that help them learn science better. Four learning units were implemented in a science classroom of 29 ninth-grade students at a large public secondary school of a small town in Central Thailand. "Two-stepped" open-ended questions on four real-world problem situations and ten-multiple choice conceptual questions were administered before and after instruction. Observation and worksheets were analyzed to reveal how students learned science, had productive conversations, and solved problems. Quantitative data suggested that students in the DBSP[superscript +] program did indeed learn content and problem-solving skills as expected. Students also improved in their communication skills. Qualitative data suggests that the communication scaffolds were one of the reasons that students learned effectively in the DBSP[superscript +] program.