Students bring admission money. Parents dig deep to pay for a Lunchable. The school district ponies up the expense of bus fuel and a driver. The PTA might even subsidize the trip. I want my field trip to be meaningful to my students - either an introduction to something we're going to work on in class or a confirmation that what we have already done has a real-world application or connection. I want my field trips to be extensions of our class - not just a vacation from preparing lesson plans or a reward for ending the year. I want my trips to be academic.
I don't know the history of schools taking field trips. I wonder when they began. What was the first destination? But I do know that they were meant to be experiential in nature. If students can't experiment something outside their norm, there is no reason to attend. And usually, if you wait until the last month of school to take one, you're probably just scheduling a day out of obligation.
I wish we had more opportunities to "study abroad", outside of the four walls of the classroom. I wouldn't mind leaving the school building on a cold wintery day to spend some time in a historical museum or shadowing workers in a manufacturing plant. I wish we could see science and math at work in the real world. We take trips to caves and museums, not because we have cabin fever after a long winter of being cooped up, but because there is academic merit in the trips. I want to take those trips when they are relevant to the curriculum, not because they are mandatory by the district or because we need to stretch our legs.