Library and Archives Catalog: Search [name of school] and [photographs] in the catalog, limiting your search to local government records. You will then find a listing of any record sets which have photographs within them. Sometimes these collections stand on their own as photograph collections, other times photographs are mixed in with other paper records. In addition, you can narrow your search by selecting photographs, photograph albums, and scrapbooks within the Genre filter.
Collections Online: Search here for individually cataloged photographs. Use the name of the school as your search term. Note: put the school name in quotes to search it as a phrase. You can also use the term "school" and then limit your search by place to the town of interest and the material type to "photographs."