Across the country, teachers’ unions have demanded bigger budgets for both salaries and classroom supplies, smaller class sizes and additional support personnel, such as nurses and guidance counselors — the issues at the heart of the current conflict in Chicago. Along the protest lines on Thursday, teachers stressed that their biggest complaints were not about their own salaries, but concerns about equity for all of the city’s public school students, including those on the West and South Sides, where schools have been closed in recent years.

Many parents voiced support for the teachers — a Chicago Sun-Times survey conducted before the walkout suggested that nearly half of Chicago voters surveyed said they would support a strike — though some said they were scrambling to come up with alternative arrangements for their families, and worried about how long this might go on. They weighed what it would mean for college applications, for sports seasons, for daily routines.

On the city’s Far North Side, Eric Ndedi, the father of two boys — ages 14 and 9 — said he had kept his children home with their mother even though school buildings were open.

“It’s more safe than going when there is no teacher,” said Mr. Ndedi, 42, a ride-hailing driver who said he had been accustomed to teachers’ strikes while growing up in the Democratic Republic of Congo, but had not previously experienced one in the United States. “It’s better to stay at home.”

Mr. Ndedi, who moved to Chicago three years ago, said he did not know enough to say who was to blame for the strike, but that “it’s totally not good.” He said he expected his sons to spend the day watching television, and hoped they would be back in class on Friday, although negotiations appeared unlikely to be resolved immediately.

Another parent, Lori Novak, whose 6-year-old son, Daniel, spent his day in a neighborhood center program on the North Side, expressed support for the Chicago Public Schools teachers. “My personal feeling about all this, and the way I’m explaining it to my son, is that the teachers are trying to make all of C.P.S. better,” she said. “I explain we’re in a very fortunate neighborhood where parents can rally and offset the difference.”