Curricular means “about the curriculum”: the planned courses and content a school or university wants students to study. A curricular change is a change to what is taught, not merely to the building or the bell times. You will meet it in school and university English, often beside extra-curricular: curricular work is inside the official programme; extra-curricular clubs, sport, and music sit outside it. It is a formal, institutional word. Students rarely say it in casual talk; teachers, documents, and websites do.