Generally, physics courses are offered in the second grade and chemistry courses are added in the third grade. The reason why physics and chemistry classes are not offered directly in the first grade is because of students' ability to accept. The first-year students who have just entered junior high school are also influenced by the learning concepts and habits of primary schools, so it is not suitable to offer theoretical subjects such as physics and chemistry in the first grade, and they need junior high school mathematics knowledge as a foundation.

On the other hand, learning junior high school physics and chemistry requires a certain mathematical foundation, so general physics courses are offered in the second grade, while junior high school physics and chemistry need to do experiments in the learning process, and these experiments are dangerous and require certain knowledge as the foundation, so physics and chemistry courses are not offered directly in the first grade.