My Teenage Girl

The show starts with performances by the mentors known as the "homeroom teachers", who would assess the contestants known as the "students" and help them succeed in the show. Shortly after, Yoon Kyun-sang was introduced as the host of the show known as the "messenger" and explains the first mission known as the "Entrance Exam". In the first mission, the contestants perform their songs introduced in Hesitation Before Going to School and each would be assessed by the audience and the mentors. There are two rounds for each performance. To pass the first round, the contestants must receive at least 75% of the votes from the audience before being assessed by the mentors. To pass the second round, each contestant must receive at least 3 votes from the mentors before being sent to a classroom according to their group. Only 40 contestants (10 from each group) would move on to the second mission while those who fail a round or have their group full would be eliminated. 23 contestants performed first in this episode, with 15 moving on to the second mission and the other 8 being eliminated after failing a round.

The first mission continues with performances by 26 contestants. During the mentors' assessment of one of the performing teams from Grade 3, Ryou Jayhyun was mistakenly eliminated after the voting system miscounted her votes with 2, but was able to move on to the second mission after another vote from one of the mentors was added to the voting system, leaving a total of 3 votes for Ryou Jayhyun. Unaired performances by some performing acts were aired with results for each performing act. Out of all 26 contestants who performed in this episode, 21 moved on to the second mission while the other 5 were eliminated after failing a round.

The first mission continues with performances by the other 34 contestants. At the end of the first mission, the remaining contestants noticed there would be a change on the number of contestants who would move on to the second mission. Due to an excessive number of contestants, each group would have 16 contestants instead of the original 10 and some contestants who were originally eliminated returned to the show, bringing a total of 64 passers for the first round. The mentors held a meeting to discuss and decide who would mentor each group. The results for the mentors were revealed and were assigned a group: Jeon So-yeon became the mentor for grade 4, Ock Joo-hyun became the mentor for grade 3, Kwon Yu-ri became the mentor for grade 2 and Aiki became the mentor for grade 1. Following the addition of originally eliminated contestants, the second mission known as the "Grade Battle" was revealed. In the second mission, each group competes against each other and would be assessed by the audience and the mentors. The winning group is exempt from elimination and the other groups face elimination. After the mid-point check of each group, the mentors noticed only 40 contestants (10 from each group) would actually perform in the second mission, meaning they would be forced to eliminate 24 contestants (6 from each group) from the show. The 6 contestants from grade 2 who performed poorly in the mid-point check were eliminated first.