True/False and Inference in a Sleep Survey
Text: A 2024 survey of 1,150 secondary students in A Coruña found that those who used screens in bed for more than 45 minutes reported 38 minutes less sleep on school nights than peers who did not. The researchers, from the University of Santiago, stress that the study shows an association, not causation. They also note that 62% of the screen users said they checked messages after midnight. The report recommends that schools start no earlier than 8:30, but the regional education department says no change is planned for the 2025-26 year. Candidate answers: (1) True/False/Not stated: 'The study proves that screen use causes less sleep.' Candidate writes True. (2) 'Why does the report recommend later start times?' Candidate writes: 'Because students are addicted to their phones.' The candidate asks why both answers lost marks.
1. Evaluate answer (1). State the correct option and explain the textual evidence, including why the candidate's choice is a trap.
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Correct option: False. The text explicitly says the study shows 'an association, not causation'. The 38-minute difference is a correlation between reported screen use and reported sleep, not proof that screens cause less sleep.
The candidate's trap is equating a strong reported finding with proof. 'Proves' and 'causes' require causal language or an experimental design; neither is present. In a True/False/Not stated item, a statement that is stronger than the text must be marked False, not True.
2. Evaluate answer (2). What is wrong, and what would a full-credit answer say?
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The candidate introduces addiction, which is not in the text. The text says 62% checked messages after midnight and that the report recommends later starts, but it does not claim that students are addicted. This is an unsupported inference dressed up as a reason.
A full-credit answer would say: 'The report recommends later start times because students who used screens in bed reported less sleep on school nights; a later start would partly accommodate that sleep loss.' It should keep the cautious wording 'reported' and avoid claiming causation.
3. Write one sentence that distinguishes a stated fact from an inference using this text.
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Stated fact: 62% of the screen users said they checked messages after midnight. Inference: some students may find it difficult to stop checking messages at night, but the text does not measure addiction or willpower. The first sentence is directly supported; the second is a reasonable guess that goes beyond the evidence.