Whoo... Things sure have changed in schools since my Mom taught there back in the 50s! That was wayyy back in the past in California! But I’m not sure she belonged to a union or anything. She’s taught in Maryland (substituted at times)and Utah (mostly Cali. and Utah)full time.
She said she didn’t want to get into the teachers’ unions because they were too expensive, I think. She definitely wouldn’t join w/them now; especially since they’ve gone even more left-wing than they were back when she was teaching!