Lois Lowry at times leaves important, seemingly familiar events unidentified. Why does she make this choice with the Giver’s memories of Christmas (or another winter holiday) and war?

I think Lowry wants the reader to identify the moments because this gives added sense of context to the reader. The reader can add their own images to what Jonas is feeling be it a warm Christmas or the ravages of war. Lowry can use indirect representation to illustrate her point more effectively than simply telling the reader what the memory is.