There are other methods that can be effective. I'm thinking specifically of work-to-rule and refusing to take on additional responsibilities like after-school clubs or tutoring. Striking is a last resort, obviously, and it's very noticeable, but it's not the only way teachers can get their point across in a public way. I just wanted to point out that not all union workers have the right to strike. It's illegal for teachers to strike in my state, even though we have a union.