Teachers in Chicago returned to the classroom yesterday, ending a seven-day strike that focused national attention on the issue of school reform.

Television viewers and newspaper readers learned about the fierce battle in Chicago between reform-minded Mayor Rahm Emanuel and the union representing 26,000 city schoolteachers. Key issues included Emanuel’s demand for lengthening what is the nation’s shortest school day and the challenge of how to evaluate teachers. There was also debate over the ability of a principal to hire the best- available teacher rather than the one with the most seniority.

A school strike that gains national attention is rare, but also helpful in allowing more people to understand the challenges in public education.

Prior teacher contracts in Chicago had somehow — and perversely — resulted in students spending just 5 hours and 45 minutes a day in school. Emanuel rightly pushed more time in class, demanding that students spend closer to seven hours a day at school.

The cumulative effect of Chicago’s short school day meant that over the course of their K-12 careers, Chicago schoolchildren missed the equivalent of three years of classroom time, compared to students elsewhere. How could they receive a decent and competitive education?

Following the same logic that more class time is good for children, Emanuel also pressed for teachers to work 38 weeks a year.

Public education is often seen as an equalizer, to help children from disadvantaged backgrounds escape that cycle and have a chance for a better life. But with the shortest school day in the country, a short school year and no method to evaluate teacher effectiveness, the 350,000 children of Chicago and their parents have been shortchanged.

Given that many of the students in the Chicago school system come from low-income, single-parent homes, lengthening the school day and the school year are sensible ways to help the children.

The Chicago school system produces dismal statistics: One in four children fail to graduate from high school, and a shamefully small percentage make it to college.

The average teacher salary (not including benefits) in Chicago is $76,000, which puts it near the highest in the nation. That compensation level is nearly $20,000 more than that of the average Chicago private-sector worker with a college degree.

Given such poor academic results and such a troubling salary gap, public support for the union decision to strike was weak.

The pattern of awarding major wage increases without changes to the terms of teacher contracts that would improve education outcomes for children were what forced Emanuel to take a tough stand — for the children and parents of Chicago.

The Chicago teachers strike failed to win political support from President Barack Obama, whose administration backs many of Emanuel’s reform objectives. The Obama administration’s efforts to improve public education across the country includes teacher evaluation and accountability. The president’s silence on the strike was calculated to avoid weakening union support for his re-election.

The end of the strike is welcome news for the parents and children of Chicago. Issues, like the length of the school day and school year and how best to evaluate teacher effectiveness, should be better understood by taxpayers across the country.

With Emanuel’s efforts, education reform is finally coming to Chicago. Reform efforts are more advanced in other cities.

In New York City, for instance, Mayor Michael Bloomberg’s insistence that teacher tenure should not be automatic resulted in a dramatic change; just 55 percent of third-year teachers in New York were granted tenure in 2012, compared with 97 percent in 2007.

The challenges in public education are complex, but the current system is failing — the children, their parents, taxpayers and the country. Reform efforts must continue to advance, and unions should join those efforts rather than try to derail them.