How should undergraduates choose classes and extracurriculars if they might apply to law school later?

You do not need to build your entire college plan around law school this early. For law school admissions, the biggest undergrad factors are GPA and, later, your LSAT or GRE score. That means your best strategy is usually to choose a major you genuinely like and can do very well in.

There is no required major for law school. Political science, history, philosophy, economics, English, and public policy are common, but admissions offices also admit students from STEM, business, arts, and other fields. A strong GPA in any rigorous major is more helpful than picking a “law-related” major just because it sounds relevant.

For classes, focus on skills law schools value: strong reading comprehension, analytical thinking, clear writing, research, and discussion-based argument. Courses in writing, logic, philosophy, history, political theory, economics, constitutional law, ethics, statistics, and advanced social science research can all be useful. Writing-intensive classes are especially valuable because legal study involves a lot of close reading and precise writing.

For extracurriculars, there is no single best activity. What helps most is sustained involvement, leadership, and evidence that you care about something beyond just resume-building. Debate, mock trial, student government, campus journalism, tutoring, advocacy groups, legal aid volunteering, community service, and research can all make sense, but only if you actually want to do them.

Depth usually matters more than collecting a bunch of random clubs. If you spend three years seriously involved in one or two organizations, take on responsibility, and can explain what you learned, that is typically stronger than joining six pre-law activities with little impact.