DD is 5, and in assembly today the children were shown a short video about the Paris attacks. Might have been the Newsround one - from what I've read, it sounds similar. I asked her for context (did the HM talk about the attacks before or after the clip?) and she said she didn't know. I'm a bit baffled as to why a school would feel it was their place to show a load of 4, 5 and 6-year-olds (it's a new school with only reception-year 2) this.
We've talked to DD about what happened - she saw we were upset on Saturday and while we didn't have the TV on DH and I discussed it a bit and answered her questions. Tonight at bedtime she was scared and worried.
Would you mention this to the HM or your child's teacher? I don't think it's a school's place to show this to children - not such small ones, anyway.