The Five Minute Teach (5MT) serves as both a training tool for graduate teaching assistants (TAs) and a format for explicit discipline-based writing instruction. Here the authors describe the development and execution of the 5MT as part of a professional development course for TAs in the sciences. Specifically, the 5MT uses learning objectives and a structured lesson plan template to help TAs design writing-related activities. In addition, the 5MT encourages TAs to provide undergraduate students with additional writing support in courses that have limited time for adapting instruction to meet student needs. The authors used surveys and reflection prompts about the 5MT to gather self-report data from TAs in a writing-intensive pedagogy course. Data collected show that TAs view the 5MT as a creative, effective way to practice designing lessons that engage students in learning the conventions of scientific writing. They also believe the 5MT approach can help undergraduates improve their writing in small, yet productive, increments. In conclusion, the 5MT serves as a pedagogical training tool as well as a potential intervention to improve writing instruction in undergraduate science courses and could benefit TAs in a variety of disciplines.