When a new discipline such as Requirements Engineering (RE) emerges and starts spreading, we are confronted with the challenge of teaching it, both by educating students and training professionals in practice. In this keynote, I will start with a historic perspective, looking at the attitudes to Requirements Engineering in the past 50 years and their consequences for teaching RE. The main focus of my talk will be on presenting and analyzing the challenges of teaching RE. Challenges to discuss include the problems of motivation, context, principles vs. methods and tools, process, and real stakeholders. I will also reflect on the consequences of these challenges in terms of both what to teach in RE and how to teach RE – and on what that means for today’s RE education and training.