PISA data show that students who use AI for specific schoolwork tasks, such as summarising texts, drafting or conducting research, attain lower scores in science than students who do not use AI. In these scenarios, students who do not use AI outperform those who do, on average, by around 20 points – equivalent to being around one year of schooling ahead of their peers. However, weekly users of AI for general purposes have similar performance outcomes to non-users. Students who regularly use AI for general purposes, and have learning opportunities at school to develop AI literacy skills, tend to have slightly higher scores in science. However, these opportunities are more common among socio-economically advantaged students, risking a growing AI divide.