One focal point of science learning is to develop students' ability to actively participate in discussions of socio-scientific issues (SSIs) in their daily lives. This study proposed the SSIs-Online-Argumentation Pattern (SOAP) to develop a pedagogical strategy enabling students to participate in online argumentation of SSIs. Two quasi-experiments were conducted to investigate the variations in scientific competencies and sustainability attitudes of students following the SOAP strategy. The participants were 127 senior high school students and 68 undergraduates respectively. Students' scientific competencies and sustainability attitudes were assessed using quantitative methods. The results showed that the SOAP strategy led to differences in high school students' scientific competencies. The mean scientific competency of the experimental group was higher than that of the comparison group in the post-test and in the delayed test. Specifically, for the constructs identifying scientific issues and using scientific evidence, the difference between the two groups did not reach significance in the post-test and in the delayed test. The results showed that the SOAP strategy resulted in differences in undergraduates' sustainability attitudes. In the post-test, the mean sustainability attitude of the experimental group was higher than that of the comparison group. Specifically, for the constructs of economic aspect, the post-test difference between the two groups did not reach significance. Finally, this research proposed suggestions and implications for future studies related to SSIs and science education. This study proposed the SSIs-Online-Argumentation Pattern (SOAP) to develop a pedagogical strategy.Two quasi-experiments were conducted to investigate the variations in learning outcomes.The SOAP strategy led to differences in high school students' scientific competencies.The SOAP strategy resulted in differences in undergraduates' sustainability attitudes.The SOAP strategy may serve as a reference for improving scientific literacy.