How much do Dartmouth's class sizes and student-faculty ratio actually affect the undergraduate experience?

At Dartmouth, those numbers do tend to translate into a noticeably different undergraduate experience. Dartmouth is a relatively small Ivy, so discussion-heavy teaching and professor access are not just marketing points. If you learn best by talking through ideas and being known by your instructors, Dartmouth is one of the places where that is more likely to happen regularly.

Day to day, the effect is usually strongest in the humanities and social sciences, where seminars and discussion-based classes are common even before senior year. In STEM, intro courses can still be larger, especially in popular sequences like economics, biology, chemistry, or computer science, but smaller discussion sections, labs, and office hours still make faculty and teaching support more accessible than at many bigger universities.

One thing that helps Dartmouth feel especially personal is its emphasis on undergraduate teaching. It does have graduate students, but it is not as graduate-heavy as some peer institutions, so undergrads often have more direct contact with professors, including in research settings. That can matter a lot for mentorship, recommendation letters, thesis advising, and simply feeling comfortable speaking up in class.

You would still need to take initiative. A low ratio does not mean every professor automatically becomes a mentor, and some departments are busier than others. But if you email professors, go to office hours, and choose seminar-style courses when you can, Dartmouth gives you a strong chance of getting the kind of academic attention you are describing.