St. PETERSBURG, Russia—Russians are protesting over everything from garbage disposal to hospital closures, voicing grievances about deteriorating public services as President Vladimir Putin tries to manage an economy beset by falling oil prices and international sanctions.

Over the last year alone, there have been hundreds of mass rallies, flash mobs and other demonstrations, a marked shift from less than a decade ago when publicly challenging authority over social concerns would have been nearly unthinkable for average people.

“There are more protests not by activists, not by political parties, but by just ordinary citizens,” said Anna Ochkina, head of a group that tracks protest movements at Moscow’s Center of Social and Labor Rights.

Oksana Gunker, a 38-year-old homemaker, was angry to realize one of her five children would have to travel an hour to school because of overcrowding at the one in her neighborhood. For years, local authorities that serve her sprawling apartment complex have failed to deliver on promises to build new schools.

On a chilly December morning, Ms. Gunker, who had never protested in her life, brandished a sign in front of the St. Petersburg city government building demanding to know “who is responsible” for her neighborhood’s dearth of schools.