CoolThink@JC aims to nurture students' proactive use of technologies for social good from a young age, preparing them for a fast-changing digital future through hands-on, minds-on, and joyful learning experiences. After a successful pilot in 32 schools, CoolThink's co-creators, led by The Hong Kong Jockey Club Charities Trust (the Trust), have undertaken an ambitious initiative to take CoolThink@JC to scale within Hong Kong, supporting high-quality adoption in 200 primary schools and laying a foundation throughout the system for more widespread adoption. By demonstrating success at scale, CoolThink partners hope to create a new paradigm for computational thinking education (CTE) at the upper primary level that will serve as an international model for other cities and states. To capture the lessons learned from this effort, the Trust has engaged SRI International to study the implementation of CoolThink@JC at scale. CoolThink partners began scaling CoolThink@JC in summer 2020, when a third cohort of 47 schools joined the first two pilot cohorts in teaching CoolThink lessons. Drawing on data from teacher and school leader surveys administered between November 2020 and January 2021, this baseline report sets the context for the rollout of CoolThink@JC in Cohort 3 schools. At the time of baseline data collection, the implementation of CoolThink@JC at scale was at its inception. The issues highlighted in this report are among a great many factors that will shape its adoption in schools and classrooms and its role in the larger system of CTE in Hong Kong. As this study continues, future reports will describe this progress, the experience of participants, and emerging models for the successful wide-scale adoption of CTE for primary-age students. [CoolThink@JC was created and funded by The Hong Kong Jockey Club Charities Trust, and co-created by The Education University of Hong Kong, Massachusetts Institute of Technology, and City University of Hong Kong.]