题目内容：

    Reducing class size has traditionally been seen as an important way to improve a student’s  educational experience. Many often believe that smaller classes would permit teachers to give more personal attention to their students. 1..

But one recent study suggests there's not much research-based evidence to support this idea. The research was collected by a team from Denmark's Danish Center for Social Science Research.

The study notes that one of the main problems with reducing class size is that it can have very high costs. 2.. Financial limitations make it very difficult for many schools to reduce the number of students in the classroom.

The new study began by examining 127 studies on classroom size. Its goal was to examine the major research studies already completed on the subject. 3.. In the end, the research centered on 10 main studies with possible sampling (采样)problems.

The researchers concluded that there's some evidence to suggest that reducing class size may lead to some improvement in a student 's reading achievement. 4.. They found just a 53-percent chance that a randomly selected test score from a student from a small class would be higher than the selected score of a student from a larger class. 5.. This led the researchers to conclude that there would be no benefit at all to math students in a smaller class size.

A.But they said the effect is very small

B.For mathematics achievement, the result was 49 percent

C.This can theoretically lead to improved academic results for students

D.Many public opinion studies have shown teachers favor smaller class sizes

E.The effects of larger class size can stay long after the students complete their education

F.Increasing class size is one of the most common ways school systems control education spending

G.They especially centered on those trying to measure if smaller class size led to greater academic success