The conception of Global Learning Communities (GLCs) was researched to discover potential benefits of the use of online technologies that facilitated communication and scientific data sharing outside of the normal classroom setting. 1,419 students in 635 student groups began the instructional unit. Students represented the classrooms of 33 teachers from the USA, 6 from Thailand, 7 from Australia, and 4 from Germany. Data from an international environmental education project were analyzed to describe grades 7-9 student scientific writing in domestic US versus international-US classroom online partnerships. The development of an argument analytic and a research model of exploratory data analysis followed by statistical testing were used to discover and highlight different ways students used evidence to support their scientific claims about temperature variation at school sites and deep-sea hydrothermal vents. Findings show modest gains in the use of some evidentiary discourse components by US students in international online class partnerships compared to their US counterparts in domestic US partnerships. The analytic, research model, and online collaborative learning tools may be used in other large-scale studies and learning communities. Results provide insights about the benefits of using online technologies and promote the establishment of GLCs.