In Chapter 5 of Number the Stars, why did the night seem different from a normal night?Was it because the German soldiers came, or was it because...

I believe that the underlying reason the night seemed different from a normal night was because of the whole situation involving the German threat to the Jews, and the necessity for Ellen to masquerade as Lise Johansen. Mr. Johansen had told Annemarie and Ellen that they should act like "normal sisters," and that it was all right for them to giggle and talk as they got ready for bed, but the truth was, things were not normal at all. The girls had been talking about Lise, and what they knew about her death, but their discussion was an outgrowth of the upheaval that was occurring in their lives that night. Ellen's parents had gone into hiding, and Ellen herself had been sent to stay with the Johansens as their daughter Lise as a means of "hiding in plain sight," so to speak. Everything had changed in the lives of both Annemarie and Ellen that first night they spent together, so it could not help but seem different from a normal night.

The fact that the girls perceived that it was not a normal night undoubtedly helped them when the Germans did burst into their room a short time later. As they had been readying themselves for bed, Annemarie and Ellen had enjoyed a spirit of levity, with Ellen talking about her love for acting, and pretending to be Lise. The atmosphere turned serious, however, when they sensed that the night seemed "somehow, different from a normal night" and the discussion turned to Lise's death. Having had a chance to realize the gravity of the situation, Annemarie and Ellen might have been slightly more prepared when the Germans did arrive, allowing Annemarie to have had the presence of mind to make sure Ellen removed the Star of David from her neck (Chapter 5).