English language learners (ELLs) bring a wealth of knowledge to science classrooms, yet often that knowledge is untapped by traditional instruction and assessment. As classrooms become increasingly diverse, it is critical to recognize the depth of understandings ELLs bring to classrooms to explain the scientific world around them. English language learners are faced with two challenges in the science classroom: learning subject matter and learning English. Research suggests that integrating inquiry-based science and language acquisition into the instruction may enhance learning in both domains. Observing scientific phenomena over time, like a plant or butterfly life cycle, provides a rich opportunity for ELLs to both practice writing and learn science. However, it can sometimes be difficult to see science content within the context of a struggling writer's scientific observations. Through the authors work in science classrooms with ELL students in an inclusive second-grade classroom they developed a rubric to assess ELL students' written observations of two plants growing over time. Specifically, they focused on the types of scientific observations made by students. They used this rubric, presented in this article, to analyze the writing of three students and suggest key instructional strategies to support student learning.