The National School Lunch and School Breakfast program (7 CFR pts 210 and 220) is the product of the National School Lunch act, which was declared by Congress in 1946. The program operates under the U.S. Department of Agriculture (Food and Nutrition services) and is currently monitored and regulated under the Healthy, Hungry-Free Kids Act of 2010.
The mission and purpose of the program is
to safeguard the health and well-being of the Nation's children
This program makes it possible to ensure that all children attending US public schools will get a nutritious, free or inexpensive meal in order to support further academic achievement. The program has recently been extended to the summer months in some states/districts such as GA, AL, TX, and NH to name just a few.
What happens is that, even when the student is not attending school due to academic recess, a free or reduced-prize lunch choice will still be offered at the school campus, or at a designated location in a school.
The decisions made upon which foods will be offered or sold within school campuses include the Institute of Medicines (IOM) 2007 report: Nutrition Standards for Foods in Schools: Leading the Way Toward Healthier Youth as well as the infusion of standards form several other entities dedicated to nutrition, growth, and development. This includes working groups such as the Alliance for a Healthier Generation (AHG), teams from different school districts and the Bureau of Nutrition Programs and Services. This latter agency directly aids in the final food choices because they must meet the US Dietary Guidelines for Americans. What the Bureau does is that it plans and balances out a week's worth of nutrition to decide what to offer students. Usually, there are up to four meal choices available, one being meat-free in some districts. Allergens such as eggs, berries,and nuts are usually kept off the menu due to the recent outbreak of sensitivity to these foods.
The USDA, under regulation CFR 210, reimburses schools for all meals that meet what they call a "pattern requirement", meaning that the demographics of the school show severe need due to financial difficulties. High-risk urban area schools are often considered first due to the high possibility that children come from dysfunctional homes where they do not obtain the nutrition that they need to grow up and develop as best as they can.