Three months. According to official website of Chongqing Energy Vocational College, the pre-school education major of Chongqing Energy Vocational College will be forced to practice unpaid for three months. Chongqing Energy Vocational College was established in April 2009, located in Science City in the West (Chongqing) and Shuang Fu New District in jiangjin district, Chongqing. It is a full-time private college approved by Chongqing Municipal People's Government and put on record by the Ministry of Education.