Grade 4 · Central idea
The Lunchroom Investigators
Infer a central idea from a school’s food-waste investigation and explain how evidence supports it.
Suggested use: 15–20 minutes in a small group. Read, discuss, then support answers with evidence.
At Bay School, students often saw unopened food in the lunchroom trash. The Green Team wanted to help, but its members had different ideas about what to change. Some blamed the menu. Others thought lunch was too short. Before choosing a solution, they decided to collect information.
For one week, the team watched the collection area after each lunch period. An adult handled the discarded food while students recorded counts on a chart. They separated unopened items from food left on trays. The chart showed that whole apples were frequently thrown away, while apple slices were rarely left over on days when they were served.
The team asked classmates why they skipped whole apples. Several said that biting a large apple was difficult with a loose tooth or braces. Others said they ran out of time. These answers suggested a problem the chart alone could not explain. The team shared its counts and survey responses with the cafeteria manager.
The manager agreed to test sliced apples for a week, following the kitchen’s food-handling procedures. The students counted leftovers again and compared similar lunch days. Fewer apple portions were discarded during the trial. The team did not claim that every kind of food waste had been solved. Its evidence applied to one change in one lunchroom.
Next, the students investigated unopened milk cartons. They returned to their chart instead of assuming that the apple solution would work for milk. They planned to collect new counts, ask more questions, and discuss another small trial. Each investigation gave them a clearer reason for their next step.
Read closely. Find the evidence.
1. Which central idea is implied by the passage?
- A. School lunches should include only apples.
- B. Students should make all cafeteria decisions.
- C. Charts can replace conversations.
- D. Collecting evidence and testing changes can help solve a problem.
2. How do the survey responses support the central idea?
- A. They prove the menu never needs to change.
- B. They explain reasons behind the counts and guide a possible solution.
- C. They show that counting food is unnecessary.
- D. They explain why milk cartons are unopened.
3. Why does the author include the second week of counting?
- A. To show that every apple was eaten.
- B. To explain how to prepare food.
- C. To show how the team checked whether its change helped.
- D. To show that students stopped asking questions.
4. How does the final paragraph develop the central idea?
- A. The team uses the same investigation process for a new problem.
- B. The team assumes milk and apples have the same solution.
- C. The team stops using its chart.
- D. The students announce that all waste has ended.
Talk it through
The author does not state the central idea in one sentence. Explain it using details from at least two paragraphs.
Teacher answer key & teaching notes
- 1. D. The team observes, asks questions, tests a change, and compares results before deciding what to do next.
- 2. B. Counts identify the discarded apples, while classmates’ explanations help the team choose slicing as a useful trial.
- 3. C. Comparing leftovers after the trial provides evidence about whether sliced apples reduce waste in this setting.
- 4. A. The next investigation repeats the evidence-based process instead of guessing that one solution fits every problem.
Distinguish the topic, food waste, from the broader implied idea about using evidence to solve problems. The school and investigation are fictional.
Keep the skill. Try a new passage.
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