According to Official Guinness Records,
The largest etiquette lesson consists of 927 participants and was achieved by Qingdao Etiquette Cultural Exchange Association (China) in Qingdao, Shandong, China, on 28 September 2018.There were a total of 934 participants for this attempt. Due to the hot weather experienced on site, 7 participants were disqualified after they left the attempt area before the attempt was over. The participants, aged from 7 to 72 years old and were from different organizations. The lesson last about 48 minutes.
For a complete list of 2018 records, please visit 2018 Guinness Records in China.