My proposal is to develop a uniform for the high school where I work. Are there studies or articles about dress codes in high school?
I suggest you look in the Opposing Viewpoints database to find articles discussing the various issues dealing with school uniforms. You can start from the library's home page and click on the databases tab in the center of the page. Under the heading "Browse Databases by Name," click on the letter "O" to find a list of databases that start with that letter. Opposing Viewpoints will be found in that list. Open the database and type terms "dress code" and "high school". I found at least one article that listed the various sides of the topic. A list of additional readings at the conclusion of the article will lead you to more information.
If you want local information on dress codes in schools, I suggest you look in the Houston Chronicle database, found under the letter "H" of the Browse databases by name list.
You can also use the LibSearch option on the library's home page. If you enter "dress code" and "high school" in the search box on the library home page you will find a variety of materials listed in order by relevance. You can adjust your results by selecting limits from a list of options on the column to the left of the text.