Extreme political correctness in teaching

Apparently, teachers in the UK are dropping discussion of the Holocaust because of fear of offending Muslim students. It is not clear to me why Muslim's should be offended by this fact.

Schools are dropping the Holocaust from history lessons to avoid offending Muslim pupils, a Government backed study has revealed. It found some teachers are reluctant to cover the atrocity for fear of upsetting students whose beliefs include Holocaust denial. . . .

From Fox News:

Teachers are dropping controversial subjects such as the Holocaust and the Crusades from history lessons because they do not want to offend children from certain races or religions, a report claims. . . .

From Daily Telegraph:

Some teachers dropped the Holocaust completely from lessons because of fears that Muslim pupils might express anti-semitic reactions. One school avoided teaching the Crusades because its "balanced" handling of the topic would directly contradict what was taught in local mosques. . . .