More time for home work so there is more family time. Also teachers have more time to help one individual student. And many studies show that the state test scores has gone up and now students are passing the requirements in the subjects they were struggling on like math or science.
In schools, periods/ classes are about one hour long, and the entire day is six to seven hours long. Making the school day longer makes students and teachers more tired and makes nobody excited to learn. Students should be interested to learn, not bored. Students can learn enough in the time the school has right now.
It is my personal belief that the average high school day is too long already. I don't believe students are able to retain information if it is constantly being taught to them all day long. Scientific studies suggest that the brain loses its peak abilities to retain information easily after 6 hours from the start. The would suggests that 2pm is the time of shutdown, so extending the day past 3pm would not be wise.
Extending the length of the school day is unnecessary. There is no compelling evidence that states that longer school days will lead to higher test scores and smarter students. In fact, lengthening school days could lead to student fatigue. Later in the day, it is more difficult for children to focus and therefore learning new things is more difficult. Higher quality of education should be considered before increasing the quantity of education.
The school day is long enough to encompass what teachers have to impart. The true focus in making schooling more effective needs to rely on the content educators deliver upon their pupils. More time in the day will fatigue students and make them less inclined to learn, so it is better to focus on upgrading educational offerings than generating longer daily schedules.
After children are let out of school, they continue to work by doing the homework provided to them during the school day. This reduces the time available that children have for themselves to play; they already spend roughly 7 hours a day sitting in chairs and listening to teachers. If the school day is to be extended, then it should be offset by reducing the amount of homework.