Literacy scholars have called for writing instruction to promote civic engagement, student agency, and multimodal composing. This study addressed this call by describing a research-practice partnership to reimagine writing instruction in a high school English course by incorporating human-centered design challenges. Using case study methods, we describe the process to negotiate curriculum, the divergent ways teachers implemented it, and the positive impact it had on students' attitudes toward writing. Through a transliteracies lens, we found that negotiating a (re)designed curriculum means working through tensions that can lead to new ways of thinking about writing. The (re)designed instruction centered 21st century composing practices that were inherently multimodal and resonated with students' out-of-school composing practices. This led to a positive shift in students' attitudes toward writing. The study suggests that incorporating "wicked problem" design challenges has the potential to reimagine how we teach writing in secondary education.