School pedagogies that expand opportunities for learners to build and use knowledge for meaningful purposes are resources for hope. Internationally, standards-based reforms in science education position schooling as a context for building and using disciplinary knowledge to explain phenomena and solve problems. There is also growing research evidence of the significant role of knowledge in reading comprehension. However, many young learners' access to science instruction -- a rich context for knowledge building -- is limited due to a narrowing of the curriculum to address accountability demands in reading and mathematics, especially in the early grades. Curricula and instruction that integrate reading and science offer an approach that promises to both expand access to disciplinary learning and enrich reading comprehension. This case study explored how one third-grade teacher's instructional practices supported students to activate, build, and apply knowledge with text, as she enacted an integrated project-based science curriculum. Findings revealed the teacher's practices for supporting students to activate relevant background knowledge and experiences before, during, and after reading. Findings also revealed how the teacher supported students to make sense of science ideas and vocabulary in text to build knowledge, and then leverage that knowledge to engage in science and engineering practices.