 One day , Zhou surprises the children with a written exam and leaves the classroom to speak with a visitor . Wang 's son , Wang Gui ( <unk> ) , tricks their maid 's son , Yue Fei , into completing their assignment while they go outside to play . After easily finishing the task at hand , Yue writes a heroic poem on a whitewashed wall and signs it with his name . The children then burst into the classroom upon learning of Zhou 's forthcoming return and tell Yue to escape in order to avoid apprehension . The old teacher eventually discovers the <unk> and , after <unk> at Yue 's impromptu ballad , asks Yue to fetch his mother , Lady Yao ( <unk> ) , for an important meeting . With the entire Wang household assembled in the main hall , Zhou asks the Lady for her blessing to have the boy as his adopted son and student . She <unk> and Yue takes his seat amongst Zhou 's students the following morning . Because Zhou knows Yue is poor , he commands the four students to become sworn brothers . Zhou also begins to teach Yue all of the eighteen weapons of war . 
