Background: The COVID-19 pandemic and the shift to digital learning materials have dramatically reduced the use of paper-based textbooks in higher education. In the field of engineering, students need a comprehensive understanding of mathematical concepts, which can be achieved through the use of e-textbooks. These digital learning materials can provide a more comprehensive and effective learning experience by incorporating a variety of multimedia elements, such as audio, visual aids, and interactive features. Rationale/Relevance: Mathematics students are expected to possess critical problem-solving skills, yet they are rarely asked to elaborate on and explain their mathematical reasoning and concepts through written argument in the engineering mathematics classroom. While students may excel in formula manipulation, they may still possess misconceptions about mathematical principles and concepts. A reliance on mechanical and procedural approaches, such as formula application, without proper conceptual understanding can result in serious misunderstandings of mathematics and its real-world applications. Without the ability to reason about mathematical concepts, students may struggle to connect what they are learning in class with real-world scenarios, leading to difficulties in solving practical problems. It is, therefore, crucial to foster conceptual understanding and critical reasoning skills in mathematics education, rather than solely relying on memorisation, in order to equip students with the necessary skills to succeed in their careers. Research Problem/ Research Question: This study will answer the following research question:How effective are e-textbooks in promoting conceptual understanding of engineering mathematics? Aim of the Study/Focus: The purpose of this study is to investigate conceptual learning in engineering mathematics using an e-textbook as a learning tool. Methodology: This qualitative case study explores e-textbooks as adaptive technology, with functionalities that include artificial intelligence allowing students to develop their understanding by interacting with digital text, watching videos of real-world mathematics concepts, and responding to quick quizzes on concepts; as well as practising and mastering further mathematical principles and concepts. It focuses on first-year engineering students and lecturers at a University of Technology in South Africa. The analysis of interview recordings was done with ATLAS.ti. analytical software. Theoretical Framework: The data from this study was analyzed through the lenses of cultural historical activity theory (CHAT) and Vosniadou's notion of conceptual change, allowing the researchers to explain complex real-world situations that students experience when engaging with the e-textbook to solve mathematics problems. Recommendations: The work presented here has implications for future studies of conceptual learning in mathematics research and may provide opportunities around learning engineering mathematical concepts, particularly in the context of developing countries. This is because it offers novel instructional approaches that are tailored to the specific needs and challenges of these countries.