Getting good grades in school with 成績

Kanji Explanation: Becoming and accomplishing with 成

Yukari stops by the preschool where Mina works, just as Takagi is there picking up her daughter. Yukari compares her life with theirs.

ユカリ:: 「高木(たかぎ)ちゃんは成績(せいせき)よくて　しっかりしてたし、」; “Takagi-chan got good grades and had it together.”; Literal: “Takagi-chan's grades were good, and she was dependable.”; 「ミナは料理(りょうり)が得意(とくい)だったりするじゃない。」; “And Mina's good at cooking, right?”; Literal: “And Mina is good at cooking and things, isn't she?”

Key Points

1成績(せいせき) means grades or performance results

In school contexts, 成績(せいせき) usually means overall grades or academic performance.
It is broader than one single test score.

2成績(せいせき)よくて is a casual shortening of 成績(せいせき)がよくて

The subject marker が is omitted in natural speech.
〜て links two qualities together, so she is saying Takagi got good grades and was dependable.

3The second line softens the comparison with shared-ground language

〜じゃない here is not a real question but a reminder that the listener already knows this.
〜たりする makes Mina’s cooking skill sound like one example among her good points.

ちゃん is an affectionate, informal suffix attached to names, used mainly for children, close friends, and family members.