koreanfestivals1-2, Exercise 3: Changes to the list

Model answer:

Change 1 (Children's Day): declared on 1 May 1922 by eight people including Bang Jeong-hwan, moved to 5 May in 1946, and made a public holiday in 1975. (Alternative: the 1 May holiday was "Workers' Day" from 1963 to 2025, renamed "Labor Day" in 2025 and made a public holiday in 2026.)
Change 2 (any other): the 1949 law set four national celebration days; Hangul Day became the fifth in 2005.

Two things the article does not tell us (any two): when each public holiday was first given as a day off; when any holiday was dropped; how Seollal came to be restored as a major holiday; why both "new calendar" and "old calendar" New Year names exist.
To find out: look for the statute (the Regulations on Holidays of Public Agencies) and its amendments, and for specialist histories, rather than rely on a short encyclopedia article.

Source: Wikipedia, Public holidays in South Korea.