The use of AI tools, particularly ChatGPT, has been widespread in recent years. Its application in education has been criticized by some and supported by others. In this article we present the case of a work carried out as part of a course unit in a computer science degree program in which the use of ChatGPT was not only encouraged but required. Students were asked to use this tool ethically and critically, comparing the results with bibliographical references. A questionnaire addressing students' perceptions about the work and ChatGPT usage was performed after delivering the task. Results showed that students were motivated to carry out the work and understood that its widespread use requires critical thinking and compliance with ethical principles. The teacher acknowledge that some students developed these competences while performing this task and were able to deliver a quality, well supported essay. The development of this competences was also identified by some students.