Due to the 10th Amendment of the Constitution, education is up to the states. As a result, it's generally difficult to make generalizations about American schools when it comes to curriculum and pedagogy. That said, there are some patterns we can speak to when it comes to science education.
First, it's necessary to establish that science as a stand-alone subject in K-12 schools wasn't common practice until the early 1900's. Before then, students access to science content was highly dependant on the teachers' professional training, equipment budgets, and cultural norms in the community.
The Committee of Ten report in 1894 is generally recognized as the formalization of subject-area instruction in schools. The report was the result of a collaboration between school leadership and college presidents (all white, all men). They broke into sub-committees to discussed different content area and what we think of today as "science" was spread across three different committees (from the report):
In contrast, English had its own committee and included discussions of all genres of writing. Part of what this speaks to is our evolution of what constitutes science class (pun intended).
It's difficult to say if the committees' work drove changes in schools or described changes that were inevitable. They did, though, stress an inquiry model, especially at the elementary level in their reports. The science committee reports don't include explicit statements about why students should study science or specific details about pedagogy, but they do address the role of understanding phenomenon and how to learn about them as an essential part of a well-rounded education (for college and non-college bound students.) The Natural History group made a point of stressing natural sciences should be included in elementary school so as to "interest students in nature" and that students weren't likely to develop deep content knowledge without that interest.
Although the American Association for the Advancement of Science was founded in 1848, teachers weren't an integral part of its founding. Instead, their professional organizations such as the American Science Teachers Association and the American Council of Science Teachers often held conferences that overlapped with the AAAS. Early conference notes speak to teachers' desire to introduce and teach science in such a way to spark interest in the content. So, in effect, as long as American teachers have been talking about how to teach science, they've been talking about ways to make it fun. Likewise, students learn science content in schools because schools reached the consunsus it's content essential to being an educated, well-rounded citizen.