Thousands of teachers and other school workers have walked out in Sacramento. The California capital is the second major U.S. school district this month to see a work stoppage over pay and staffing shortages. In Minneapolis, teachers are in their third week of a strike. The walkouts come as schools across the country deal with fallout from the coronavirus pandemic and limited resources for granting the demands of educators and support staff. Across the country, union workers are seizing the opportunity posed by tight labor markets to recover some of the power they feel they lost in recent decades as unions shrank in size and influence. And experts expect to see more labor strife as the country emerges from the pandemic.