Dong Yi S01E47 - Child Prodigy

Geum, or now known as Prince Yeoning is shocked when he realises that the nobleman is his father. He starts to get used to the life as a prince and Dong Yi is made a level 2 concubine. Dong Yi wants her son to act stupid when in school. Jang Ok Jeong hears this and asks him to sit in on the prince's exams. But it is backfired when the prince shows his knowledge and this impress the King who wants him to study with the Crown Prince. In the meantime, the Queen who is ill knows about the Crown Prince sickness and informs Dong Yi that she wants her son to study with the Crown Prince so that he can replace the King when the time comes.