formula

Illustration of a seated elementary school student (girl)

Illustration of a seated elementary school student (girl)

Illustration of a seated elementary school student (boy)

Illustration of a seated elementary school student (boy)

Illustration of a seated person (female)

Illustration of a seated person (female)

Illustration of a seated person (male)

Illustration of a seated person (male)

Illustration of a seated high school girl and junior high school girl

Illustration of a seated high school girl and junior high school girl

Illustration of a male high school student and a male junior high school student seated

Illustration of a male high school student and a male junior high school student seated

Illustration of a seated high school girl and junior high school girl

Illustration of a seated high school girl and junior high school girl

Illustration of a male high school student and a male junior high school student seated

Illustration of a male high school student and a male junior high school student seated