It is widely agreed that ethics teaching should have an important role in Information Systems (IS) teaching. Yet, there are no studies exploring how students apply theories of ethics in their decision-making. This is unfortunate, because teaching ethics is of little practical use if the students do not utilise the acquired knowledge in practice. In order to bridge this significant gap in the literature, we introduced IS students to the following theories: utilitarianism, Kantian ethics, virtue ethics, prima-facie principles, and Rawls' veil of ignorance. We then asked them (n = 75) to apply these theories to a given moral conflict, and to assess whether they intended to use the theories in real life. Phenomenographic analysis revealed four developing levels in the students' perceptions: 1) rejection (the student trusts his or her intuition, consciousness or feelings rather than the theories); 2) latent use (the student recognizes that the theories may be latently present in intuitive deliberation); 3) conscious use (the student uses the theories to support intuitive deliberation); and 4) internalised use (the student has internalised the theories to such an extent that he or she does need to consciously steer his or her deliberation to their use). These findings entail recommendations to IS educators on how to educate students to address ethical issues through the application of theories. (Contains 1 table and 1 figure.)