https://www.cmoa.jp/title/265364/
Anne, who became a widow at the age of 25, received a surprising request to teach the sons of princes and aristocrats about sex! She seems to have been chosen because she is a young widow with experience, but in truth she had been married to an old marquis for about ten years, and is actually still a virgin. Yet, this is also a great opportunity to take care of some of her financial troubles so she takes advantage of her reincarnation and comes up with a secret plan to get through the sex education with only classroom lectures, based on her knowledge and experience gained in her previous life!
However, for some reason, even her older son-in-law Elliott was attending the class... The naive boys are blushing all the time, and is Elliot also acting strange? Her innovative textbooks and classes are gaining popularity on the street, but Anne is unable to understand communication amongst aristocrats. And her younger brother, Oliver, is always irritated by Elliott.

A hilarious and thrilling love comedy about health and physical education in another world☆