If I understand correctly, now teachers are leaving their jobs to protest.
When most people skip work to protest for higher wages, they're fired. Why are teachers special in this regard?
Teachers are using personal days or sick days to protest. That's within their rights, but it puts a strain on substitute teachers, especially the big districts where the pool is a relatively smaller shared set. If a teacher runs out of those days and continues to miss work they probably would face a stiff backlash from their districts' administration. Keep in mind that most of the state's schools are unaffected.
Get it straight that nothing of the protests is fighting for higher wages or better benefits. The fight is over the attempted neutering of specific unions, which will render it illegal for those sets of workers to ever unionize in a meaningful way. All concessions in compensation the bill asks for from public workers have now been agreed to if they leave the union alone. The protests are over whether it will be legal for them to bargain collectively in the future.
Part of what has flared Wisconsin attention to this bill, pushed by a republican governor, is that it attacks public workers unions which lean democrat and exempts the public workers unions that typically lean republican. It attacks the unions for teachers, health care, etc but leaves alone unions for law enforcement, firefighting, etc. People understand the reason for greater benefits for certain groups, but union rights is a tough one to justify splitting.