Final answer:
While an increased school day at a high school correlated with higher student performance, researchers indicate that this might be due to self-selection rather than the extended hours alone. Experts suggest that the structure of schools and incentives for success play a crucial role and various proposals aim to address these issues.
Step-by-step explanation:
The inquiry about the cause associated with the positive effects at schools suggests that you're trying to understand what leads to improved student outcomes. A high school that added an hour to its school day saw an increase in student performance on statewide tests by 10 percentage points over the previous year. However, researchers pointed out that this improvement might be attributed to self-selection, as only motivated students willing to sign a contract were part of that school. Therefore, it does not conclusively prove that a longer school day by itself improves student achievement.
Researchers argue that the increase in spending per student has not corresponded with a rise in test scores, indicating that the issue may be the structure of the school system and the incentives given for success, rather than resources alone. Proposals to address these issues include testing students regularly, rewarding high-performing teachers and schools, and giving students more choice in their education through mechanisms like vouchers. These aim to provide different incentives and structures that may better support student achievement.