Engineers must be able to collaborate with experts across disciplinary boundaries to successfully address the complex challenges of a contemporary workplace. As programming has a reflexive synergistic character, it can support a way of thinking about and exploring disciplines beyond computer science. Meanwhile, programming is a medium of communication. In this study, engineering students used authoring tools of mobile app to design an English-learning app, in which English teachers provide feedbacks for revision, and a preliminary cross-disciplinary collaboration is asserted. The learning design referred to the frameworks of constructing socio-technical creativity to aid the students in employing their existing English knowledge to design mobile apps. The evaluation was conducted on the basis of the students' designed apps and presentation, teachers' feedback, and students' self-reports. The results indicated that the common use of mobile apps in daily life seemed to create a boundary object for the engineering students and English teachers to express, communicate, and coordinate their perspectives and knowledge. Students could view the engineering work from different aspects and value English teachers' expertise. By accounting for the interests of students and schools' limited resources, this study serves as a reference for developing a method of cross-disciplinary learning and collaboration. Implications for practice or policy: (1) Students can acquire knowledge of English as well as programming skills in an instructional software design activity; (2) Cross-disciplinary collaboration could be enhanced by using mobile application as a boundary object; and (3) Teachers could use instructional software design activity to promote cross-disciplinary learning and collaboration for engineering students.