Just to update anyone interested -
I went in (calmly!) to speak to the teacher after school yesterday - As my daughter's only been in her class a month I hadn't spoken to her before. She looked extremely guilty when I said that DD had been very upset by looking at graphic images online, and said it had been ' a mistake.' Here I get confused, as my daughter is saying one thing and the teacher another. The teacher says that they were all two to a laptop, doing a project on Anne Frank, and in their pairs looking for pictures of her to include in their work. She claims DD must have 'put concentration camps' into the search engine, as the disturbing images some posters have described came up.
DD got very upset when I asked her if she had put those words into google herself and she insists no, why would I want to search for that? She claims that her and her partner had just about finished their work, and the teacher came over and suggested they search google images for 'concentration camps - she was stood over them as DD typed it in.
I don't know how the teacher cannot have been aware of what would come up, although she claimed to have been 'shocked' herself. When I asked whether there were any internet filters in place to protect the children from graphic imagery like that, she said no, and she would 'have to speak to the computer technician about it.'
Obviously now, it is difficult for me to take it further as it is her word against DD's. With DD having so much difficulty coping with learning about WW2 anyway, I don't see her typing 'concentration camps' into google off her own bat. Like all kids she has her faults, but lying isn't one of them. And if it had been the case that she had put it in her herself, the teacher would surely not have even been aware she had done it - She would have felt shocked and guilty and turned it off straight away. It doesn't ring true somehow....
I have talked it through with DD as best I can, and have decided not to mention any more to her for now. Like I said in my original post, I have no problem with her learning about these things. They happened and she has to know that they happened. But this should be done in a careful way, not by searching google when there are no suitable filters in place. She stumbled upon these pictures without any understanding or context, and instead of making her feel deeply shocked but knowledgeable, they just made her feel afraid.
This is actually the second time we have had trouble in that school with their internet filters - Last year, she came home to tell me that she'd put something into google and had to tell the teacher as it came up with '20 ways to a woman.' (!!!!) I think they need to change their technician.....