If the teacher had invited the children to share their thoughts then I am 99% confident they would have settled down and been ready to listen. The fact that she shared something about the book and not some unrelated remark doubles my suspicion that here is a teacher at the end of a term that can't end soon enough, phoning it in. I can't know for sure, but I have seen classrooms where the teachers have done as I have described and they have been able to start and continue uninterrupted.
The other information about this teacher indicates that she sees the inclusion of three latecomers to school as an imposition on her, a disruption to her class; she has not been to bothered to do the extra work the arrival of those children should have entailed for her, they are not on the birthday board, etc. The child was sent on to the after school club crying. So putting it all together, I am forming a picture of a teacher who is a bit lazy, resentful, tetchy, and inclined to wallow in a feeling of being put upon.
LeQ -- 'I don't think a teacher expecting a 4 year to do as they're told, when asked, and then reprimanding that child for deliberately ignoring the request is what most people would call harsh measures is it? Is it, really?'
Mathanxiety -- 'LeQ, it is both harsh and completely unrealistic, and if reprimands that result in tears are the sum total of that teacher's bag of tricks, I am sorry for the entire class, because that makes for a very unpleasant and negative learning environment for everyone. '
Don't quote selectively. You think instant obedience is reasonable to expect from a four year old. I think that is unreasonable and I think that a reprimand in that case is harsh and also unreasonable. Instant and complete obedience is not natural and is not reasonable to expect in a four year old.
As I said above, I think any teacher who issues orders in that fashion to a four year old is setting herself up for a 50/50 chance that her position will be challenged and is therefore an idiot (because she is an adult who is unfortunately not behaving like one) and completely unprofessional.