Given that this is a Hannity bit, it's not surprising that there is a bit of distortion to the claim.
First off - the class is not a religion class, and the textbook is not a religious textbook.
It's World History.
Given that Islam was influential in world history, particularly the ancient world, resulting in multiple Islamic nations and empires such as the Ottoman Empire, it's not surprising that there is more than just a page or two devoted to it. Discussing what they believed is certainly relevant to understanding the history of the period.
Consider this - if you removed all references to Christianity when you studied American history how could you hope to understand the forces that shaped our country - freedom of religion (due to the many sects seeking freedom from religious persecution) and why we place such a high value on religous freedom. Consequently Islam has very little role to play in American history and a discussion of Islam would be a footnote at best.
In addition, Hannity leaves out half the story - the half that balances out this so-called outrage. Here's what the textbook company has to say:
Pearson | Always Learning
In Florida, as in other states, Pearson creates custom course materials that align to the states specific curriculum standards. Floridas standards split the world history curriculum into two years of study, in grades 6 and 10. The states standards require the sixth grade curriculum start with early civilizations and continue through to the fall of Rome (476 A.D.). In the 10th grade, the states high school curriculum begins with the Byzantines (330 A.D.), proceeds to the Early Middle Ages in Europe (500 A.D.) and continues to the present day.
The Florida edition of the Pearson high school World History text aligns to the states standards, which require that the high school course includes content on the origins of Islam, while the middle school text details the earlier origins of Judaism and Christianity. The Florida Department of Education approved the Pearson World History programs for adoption and validated that the content in our programs meets the requirements and educational goals of the state.
Now why did Hannity leave out any mention of the Middle School text?