Tray Waste Part I: Determine the Impact of Lunchroom Changes by Measuring Tray Waste


Making healthy changes to the school lunchroom is a no-brainer, but how do you know if those changes are really making an impact?

Schools participating in USDA school meal programs are faced with regulations that dictate what foods kids can take as components of free and reduced meals. While these regulations require that the healthier foods be on the tray in order for the meal to be fully reimbursed, many students simply throw away unwanted components of the meal once they leave the lunch line. Thus the fruits and vegetables that kids toss are not providing them with any nutritional benefits; instead, they are adding to the cafeterias waste!

The Smarter Lunchrooms Movement has identified research proven methods that increase consumption of the healthy foods kids need. These strategies have been shown to increase consumption, decrease waste, improve the cafeteria’s bottom line, and improve student’s nutrition. Once one of these strategies or programs is implemented, it is important to assess the impact it is having. By measuring tray waste, you can to determine whether the change is beneficial to your business and have evidence to share with interested stakeholders, including school administrators and community members.

Collecting tray waste data doesn’t have to be a huge, expensive and daunting task! New research from Cornell University shows that a simple method, coined the Quarter-Waste Method, is a reliable, quick, and easy way to accurately measure food waste. While literally weighing each student’s food waste with a digital scale is the most accurate method, it is time consuming and costly to do so. A viable alternative is the Quarter-Waste Method which is nearly as precise (90% reliability) as weighing. The method involves a visual estimation of food remaining on a student’s plate or tray. When students bring their tray to the waste basket, the researcher or data collector simply records whether ¼, half, ¾, or all of each food they can identify has been eaten. These percentages can then be used to calculate weight of food being wasted.  

The Quarter Waste Method was tested by Cornell University researchers in a kindergarten through 5th grade lunchroom that served a total of 197 lunches. The study found that the quarter waste method is more effective at accurately and efficiently measuring waste than other visual methods including the half waste method and taking  photographs of the waste. With this new method, measuring the impact of changes in your lunchroom can be done for no cost, with little hassle to staff or students, and can be done in only one school day.

For a guide to using this method in your lunchroom see:  Tray Waste Part II: 5 Simple Steps to Efficiently Measure Tray Waste 

Photo source: Free for non-commercial use


Katherine Baildon, Cornell Center for Behavioral Economics in Child Nutrition Programs


Hanks PhD, Andrew S; Brian Wansink PhD and David Just PhD. “Reliability and Accuracy of Real-Time Visualization Techniques for Measuring School Cafeteria Tray Waste: Validating the Quarter-Waste Method.” Journal of the Academy of Nutrition and Dietetics. (2013). DOI: 10.1016/j.jand.2013.08.013.