The release of ChatGPT in late 2022 caused activity and concern in academic and educational communities. Some consider the technology’s ability to generate human-like text that passes at least cursory inspections for factual accuracy “often enough” a golden age for information retrieval and computer-assisted learning. Others, on the other hand, worry that the new tools may lead to offloading of cognitive tasks and unprecedented levels of academic dishonesty. In this work, we quantify some of the effects of the emergence of Large Language Models (LLMs) on online education by analyzing a multi-year dataset of student essay responses from a free university-level MOOC on AI ethics. Our dataset includes essays submitted both before and after the release of ChatGPT. We find that the launch of ChatGPT coincided with notable changes in both the length and style of student essays, mirroring observations in other contexts such as academic publishing.