The emergence of generative artificial intelligence (GenAI) has ignited intense debates regarding its potential benefits and detriments for education. Despite such widespread discussions, insights into GenAI's impact have often been limited to anecdotal evidence and a narrow scope of educational stakeholders. To understand the broader response to GenAI tools in education, we collected and analyzed public online discussions of ChatGPT, a leading GenAI tool, in the first four months following the tool’s release. We collected 345 posts and 6,463 comments about ChatGPT from 25 education-focused subreddits. We analyzed the volume, engagement, and content of ChatGPT discussions through descriptive statistics and natural language processing techniques. Findings show relatively low volume of ChatGPT discussions, unevenly spread across education-related subreddits—with the majority of the discussions occurring in two subreddits while six subreddits did not have any discussions. Despite this, the level of engagement within ChatGPT posts was substantial; for instance, a ChatGPT post hosted a median of 15 comments, and these comments were lengthy, indicating rich engagement rather than superficial. The content of ChatGPT discussions across the six largest education-related subreddits differed in the degree of analytical thinking and emotional tone even while sharing a predominant focus on students and AI. Diverse reactions to and perspectives on GenAI—observed from varied levels of volume, engagement, and content of ChatGPT across educational-related subreddits—highlights how diverse educational stakeholders reacted to GenAI differently, offering insights into how to explore, analyze, comprehend the spread and adoption of technological innovation in education.