This study explored the usefulness of the open dialogue strategy to help Saudi Arabian primary teachers teach, and fourth-grade students learn, the key biological concept of classification, which is a significant challenge for students to grasp, especially the concept of humans versus animals. The convenience sample comprised N = 84 Grade four students (50% female, 50% male) in the 2018 Autumn term from four schools (two boys/two girls) in one city in the Northern region of Saudi Arabia and four (N = 4) teachers (self-selected sampling), one for each of four classes. A content and conversational analysis of translated and transcribed transcripts of the researcher's classroom observations, interpreted through the communicative approach, the Intermental Development Zone (IDZ), and exploratory talk, affirmed the effectiveness of open dialogue in Saudi primary science classes. Findings showed that, to move through the dialogue process and learn about the scientific concept of classification, students drew on (a) their religious views, (b) their personal religious beliefs and (c) the notions of Darwin's theory of evolution and Islamic creationism. Findings affirmed that using dialogue in primary science classes helped students learn aspects of the Saudi science curriculum. Findings further supported preparing preservice and inservice Saudi science teachers in both planned and open dialogue teaching strategies.