Shanghai is looking into the number of school assignments that primary and middle school students are required to complete, part of the city's efforts to ease the academic burden on students.

“The investigation is being conducted on the basis of students' grades and ages. We want to find out the specific conditions of students' homework. The results will provide a reference for us to find a better way to ease the burden on students,” said Yin Houqing, an official with Shanghai Education Commission, on Thursday.

“It would be unrealistic to do away with homework for students. The question is how much school work they have and what format is really best for students. We hope that the investigation will provide us with useful information,” he said.

Yin said some preliminary results from the investigation will be released in the next few months.

According to a report released by the Paris-based Organization for Economic Cooperation and Development on Tuesday, Shanghai students continue to outpace the world in terms of grades. The city's teens are still the world's best at reading, math and science.

But the survey also reported that students in Shanghai spent the most time doing homework, about 13.8 hours every week, almost three times the report's average of 4.9 hours.