Measuring tray waste can give insights into what foods kids are eating and what foods are being thrown away. In order for the healthy foods to give students nutritional benefits, they must first eat them! Before and after implementing changes in your lunchroom, collect tray waste for comparison. This empirical data can help you determine what healthy eating initiatives are effective and can also give school administrators and community members evidence of lunchroom successes!
Materials: Scale, a long table, spreadsheet & pencil to record data
Download Spreadsheet and Example:
Example Spreadsheet You will want to fill in your spread sheet with the names of the foods to be served on the day you are collecting plate waste in advance.
Weigh Foods: Prior to the lunch period, weigh each food item being measured. To get the most accurate measurement, weigh at least three different servings and take the average (sum of the weight of three divided by 3). Determine the weight of each empty tray, plate, and/or bowl or other packaging (if there is any) that the food was weighed in. Subtract this number from the averaged total and the new total is the approximate weight of the item. For items that are pre-packaged, just record the weight that is given per serving on the package. Weighing servings not only helps you visualize a portion size but also can be useful in determining the nutritional value of consumed or wasted foods (see Part III. for more information about calculating nutritional value).
View Portion Sizes: All tray waste data collectors should familiarize themselves with what one portion of food looks like. This can be done can while taking the pre-weight. This way, they can more accurately estimate how much of the portion is remaining when the trays are discarded.
Set Up a Station: Prior to students’ arrival, set up a station at which trays will be collected. If possible, put the station near where students normally return their trays so that the change in the environment is less disorienting.
Collect and Record Data: Ask students to place trays on the table and as each tray comes in estimate how much food is left on the tray using the following Quarter Waste Method:
- Enter a 0 for none wasted.
- Enter a 1 for ¼ wasted.
- Enter a 2 for ½ wasted.
- Enter a 3 for ¾ wasted.
- Enter a 4 for all wasted.
- Record the observations on the spreadsheet provided.
- If you can’t tell whether or not an item was on the tray, leave the corresponding space blank.
- Only enter data for food wasted that you can identify.
- Note that each numbered column represents a specific tray.
Once you have estimated are recorded each food item, you will be ready to analyze the data that you have collected! Tray Waste Part III: Analyzing Tray Waste Data Made Easy
Read Part I Here: Tray Waste Part I: Determine the Impact of Lunchroom Changes by Measuring Tray Waste
Drew Hanks, Cornell Center for Behavioral Economics in Child Nutrition Programs
Katherine Baildon, Cornell Center for Behavioral Economics in Child Nutrition Programs
“Tray Waste Entry Protocol.” Smarter Lunchrooms Movement
For More Information
Tray Waste Part I: Determine the Impact of Lunchroom Changes by Measuring Tray Waste
Tray Waste Part III: Analyzing Tray Waste Data Made Easy
Related Videos: Smarter Lunchrooms Movement: Plate Waste, Data Collection, & Experimental Design