What were the consequences of changing the bell schedule mentioned in class?

• A. Later bell times increased crash rates
• B. Later bell times decreased crash rates by 16%
• C. Later bell times had no effect
• D. Earlier bell times increased crash rates by 8%

Answer: (B)

The main idea is that aligning school start times with how teens naturally sleep can affect safety outcomes. When bell times are delayed, students get more sleep, which improves daytime alertness, reaction time, and judgment behind the wheel. That boost in alertness helps reduce the likelihood of car crashes. In the class example, delaying the start time was associated with a 16% drop in teen crash rates, making this change a meaningful safety benefit.

So the best choice reflects that later bell times lowered crashes by about 16%. The other scenarios — more crashes, no change, or earlier start times increasing crashes — don’t fit the observed safety impact of delaying start times.