The Lunchroom Litter Problem
A fifth-grade class notices that the school lunchroom has a lot of litter on the floor - mostly wrappers and napkins. The principal asks them to reduce litter. The class surveys the lunchroom for one week and finds: 240 wrappers and 180 napkins on the floor, most near the trash cans and the exit door. They have a budget of $50 and one month to show improvement. They brainstorm three ideas: (1) add more trash cans near the doors, (2) put up posters reminding students to throw away trash, and (3) start a "litter patrol" where students pick up trash during lunch.
1. The class can only afford to try one idea well. Using the survey data, recommend which idea to test first and explain your reasoning. Describe how they should measure whether it worked.
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Recommendation: Add more trash cans near the doors and trash-can areas first (idea 1).
Reasoning from the data: Most litter was found near the trash cans and the exit door. That pattern suggests students are missing the cans or dropping trash on the way out. Adding cans where the litter actually accumulates directly targets the cause shown by the data. Posters (idea 2) and litter patrol (idea 3) address reminders and cleanup, but the survey points to a location problem, so changing locations is the most direct fix. A $50 budget can likely buy a few inexpensive bins.
How to measure success: Repeat the same one-week litter survey after the change, counting wrappers and napkins on the floor in the same locations at the same time of day. Compare before (240 wrappers, 180 napkins) and after. A decrease near the doors and cans would support the idea that adding cans reduced litter. Keep everything else the same so the comparison is fair.
2. After adding trash cans, the litter count drops to 150 wrappers and 120 napkins. A student says, "Our solution worked - litter is solved!" Evaluate this claim and suggest one next step.
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Evaluate the claim: The data show real improvement - wrappers fell from 240 to 150 and napkins from 180 to 120, roughly a 35–40% reduction. So the change helped. But "solved" overstates it: 270 pieces of litter remain on the floor, and the survey covered only one week. Other factors could also explain part of the drop (for example, students behaving differently because they were being watched, or a different week having different food).
Next step (any one):
- Run the survey for another week or two to confirm the improvement lasts.
- Combine the trash cans with posters or a patrol to address the remaining litter.
- Survey where the remaining litter is found to see whether new hotspots appeared.
Reasoning: A single before-and-after comparison is good evidence but not proof. Engineers and scientists repeat measurements and test combinations before declaring a problem solved.