Teacher strikes are illegal

State and local public employees, including teachers, have no legally protected right to strike. State statute establishes no specific penalties for unlawful public employee strikes; in some cases, courts may grant injunctive relief to prevent or end unlawful strikes. The Legislature could enact laws establishing penalties for unlawful public employee strikes, provided that such laws are consistent with protected free speech and other state and federal constitutional rights. Washington Attorney General Rob McKennal

But there is one large problem. There is no cost to the striking teachers. They still get full pay, because the school year must be 180 days. They lose some of their summer, but none of their pay.