When watching the film I was wondering how old the children are? I assuming Jonathan is about 10 but Judy I wasn't sure about, she is made out to be a stroppy teenager, but she looked younger and when she said she started in a new school I assumed maybe she was 11 or 12.
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From what I can see (I won't be seeing the movie until January) she's just edging out of the tween years. Not quite a teenager yet, but starting to take an interest in boys.
Many thought they were supposed to be twins in the original books, but nothing ever confirmed that. I think I like that the movie is differentiating them a bit more...they were sweet and likable but a bit bland and indistinguishable from each other in the books.