The ability to write well is inextricably linked to reading comprehension, acquisition of content knowledge, and college and career readiness. Many adolescent students, especially those from economically challenged (EC) households, struggle in their ability to communicate in writing, especially in writing to explain or inform across subject areas. While high school students are expected to produce compositions and research papers, they often need the most support at the single sentence level. The purpose of this qualitative study was to explore the characteristics of students' writing in a high school serving students from predominantly ED households in a large urban setting, a school that implemented a method of scaffolded and embedded writing instruction across all subject areas. This study was framed by sociocultural theory (Vygotsky, 1978), "cognitive load theory" (Sweller, 1988), and "the capacity theory of writing" (McCutchen, 1996). Content analysis of historical student and teacher-created documents was used to examine the characteristics of writing composed by 79 ninth grade students before and after four months of exposure to the Hochman Method sentence-level scaffold, and to explore educators' perceptions of the impact of the writing instruction on their students' writing as well as their own practice. An inductive analysis of educator interviews was used to provide context for the student and teacher document analysis. Direct participants included two teachers and one instructional coach. This study extended previous research about embedded grammar instruction and writing across content areas. Limitations included the inability to interview students and time between the phenomenon and educator interviews due to school-based challenges posed by the COVID-19 coronavirus pandemic. Findings highlight the importance of students' command of the sentence in expository writing and the impact of embedding writing instruction in the content areas. Further research should be done to investigate the impact of embedded, sentence-level writing instruction on the writing of adolescent students, including English Language Learners. Recommendations for educators and policymakers are discussed. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]