Supporting students to become critical consumers of online information is one of the most urgent agendas in education today. In schools around the world, students are engaging in online information problem solving (IPS) tasks to develop critical thinking and problem-solving skills by searching and evaluating online information. This qualitative case study explored how 5th and 6th Grade students experienced online IPS using their metastrategic knowledge--that is, knowing why and how to use certain strategies in specific instances. Data collection methods included classroom observation, classroom video recording, fieldnotes, the think-aloud strategy, interviews, and students' reflections about their writing and artifacts. The study's findings indicated that students actively engaged their metastrategic knowledge during the online IPS processes to understand and examine the validity of information and sources and to effectively communicate their IPS results to others. In the process, students also developed ownership and responsibilities for problem solving with reliable information. Based on the study's findings, this article summarizes the process and discusses the pedagogical implications of elementary students' online IPS.