This paper describes the development of a coding guide that was used to evaluate the use of information and communications technologies (ICT) in student assignments. Instrument design and pilot-testing was conducted in a Hong Kong Chinese primary government-subsidised school (I-School) with a school-based e-learning project. The design of the assignment coding guide was drawn from a lesson observation guide (Tam, Chan, Li, & Pow, 2014) that was developed for this e-learning project with reference to the Research Coding Guide for Student Work (2011). The research team developed the coding guide in recognition that it is important to examine not only 21st century skills, but also how teachers make use of ICT in their assignment design to enhance teaching and learning, as well as how the assignments provide opportunities for students to practice their ICT skills. The coding guide that was developed contains 14 items that measure ICT integration into assignments. These items relate to the following broad categories: (a) Student Learning Outcomes, (b) Learning and Teaching through Assignment, (c) ICT Use, and (d) ICT Enhanced Learning and Teaching. Rating was based on sample scripts of all written assignments (both paper-based and digital) in one learning unit assessed with different levels of academic performance (high, middle and low). Thirty-six sets of assignments from three major academic subjects of Chinese, English, and Mathematics between Primary Two (P2) and Primary Five (P5) were collected in the same primary school from September 2012 to December 2014. In this period, which spanned four continuous semesters, researchers discovered that the assignments developed from paper-based dominant assignments to paper-and-ICT-balanced assignments as students were required to post their assignments through the online platform (Microsoft SharePoint). Moreover, teachers provided more chances to allow students to implement their ICT skills and creativity, such as through student assignments, which transformed from simply attaching a student's drawing to attaching a relevant picture from the Internet.