President Yoon Suk Yeol delivers a lecture about the 2023 launch of the Nuri rocket after making a surprise appearance at a class of first graders as a special instructor for the after-school Neulbom program at Ain Elementary School in Hwaseong, Gyeonggi Province, Friday.

Yoon's class involved a presentation of a video about the domestically manufactured rocket, reading the children a book about space and rockets and hands-on activities to teach the class about rocket propulsion, according to the presidential office on Friday.

Ain Elementary School is one of the 2,741 schools -- or over 40 percent of the total number across the country -- that opened the after-school Neulbom classes for first graders in March, designed to offer the students after-school classes and child care in public institutions. Yoon has touted Neulbom school programs as one way to tackle the country's continually declining birth rate.