I've met people at my graduate school who earned biology degrees from very highly-rated schools but never once had a field biology course. In every biology class I took at Principia, we went outside. That hands-on experience gives you emotional and personal contact with what you're studying. It makes it part of your life, and you remember it. Field training can be pretty demanding.
Students learn to think in new ways.
You have to love nature and love studying nature. We learn to understand ecosystems and to look logically for the solutions to problems. In biology, I had to develop the ability to write like a scientist, supporting my hypotheses or assumptions with facts. Our classes are a hybrid between lecture and team-type investigation of the material. Puerto Rico Abroad are high points for many biology majors, but some students also create their own field-study programs.