Why do Anne's grandparents disapprove of wood-carving class?

Actually, Anne's grandparents registered her for wood-carving. They disapproved of her Zionist meetings because they were anti-Zionist.

Sometimes old people have really old-fashioned ideas, but that doesn't mean I have to go along with them. I need my grandparents, but in a certain sense they need me too. From now on I'll be free on Wednesday evenings. You see, my grandparents made me sign up for a wood-carving class, but actually I go to a club organized by the Zionists. My grandparents don't want me to go, because they're anti-Zionists.