In 1899, Anna Gorenko became a student at the Mariinsky Women's Gymnasium, located at 17 Leontyevskaya Street. The compulsory subjects taught at the Mariinsky gymnasiums included: Law of God, Russian language, history and geography, arithmetic, basics of geometry, penmanship, needlework, gymnastics, "the main concepts of natural history and physics with the addition of information related to household management and hygiene." French and German languages and drawing were also taught. Unlike institutes or theological schools, which primarily aimed to prepare female students for family life, the gymnasiums provided a broader education, striving to make their graduates well-rounded individuals.

As in other gymnasiums, education at the Mariinsky Gymnasium was fee-based, starting from 40 rubles at its opening and rising to 80 rubles by 1911, which limited admission for girls from lower social classes. For example, in 1890, out of 129 students, 77 were children of nobles and officials, and only 2 students came from lower ranks and peasants. In the same year, there were 16 scholarships for underprivileged students, and daughters of employees working at the gymnasium were granted the right to free education.

"She knew how to make a curtsy by folding her hands, courteously and briefly answer an old lady’s question in French, and prayed at the Passion Church in the gymnasium."

"She studied poorly in the lower classes, then well. She always found the gymnasium burdensome. In class, she only befriended Tamara Kostyleva, whom she never met again in life."

"Two years in the 6th grade. She learned German from Frau Schultz. She was at Smolny, but couldn’t endure it—could not live without freedom. French language: when the older children were five years old, they took a Frenchwoman. 'The Queen of Spades'—a translation into French at the gymnasium. Poems—there were two friends to whom she read poems."

"I wrote my first poem when I was 11 years old (it was terrible), but even earlier my father for some reason called me a 'decadent poetess.'"

Recalling her childhood, Akhmatova wrote: "My first memories are of Tsarskoye Selo: the green, damp splendor of the parks, the pasture where my nanny took me, the hippodrome where little dappled horses galloped, the old station, and something else that later entered into the 'Tsarskoye Selo Ode.'"

Nearby, in the Tsarskoye Selo Boys’ Gymnasium, her future husband Nikolai Gumilev studied. In 1905, the family moved to Yevpatoria, and then to Kiev, where Anna completed her gymnasium course at the Fundukleevskaya Gymnasium.

Sources:

https://uznayvse.ru/znamenitosti/biografiya-anna-ahmatova.html

https://antennadaily.ru/2019/06/25/peterburg-akhmatova/

http://kfinkelshteyn.narod.ru/Tzarskoye_Selo/Uch_zav/Mariinskaya_gimn_uch.htm