Language about Islamic history in school textbooks is spurring battles across the nation, with some parents’ groups and lawmakers objecting to what they see as an overly benign portrayal of the religion’s spread and its teachings.

Following recent attacks in the U.S. and abroad by terrorists who claim to espouse Islamic beliefs, more American parent groups have turned attention to what children are taught about the religion. Muslims and their supporters say the opposition to the textbooks amounts to fear-mongering and presents a distorted view of their faith.

Kristen Amundson, executive director of the National Association of State Boards of Education, which represents U.S. state and territorial education boards, said she expects to see more parents pushing to change textbooks and curriculum this year.

“We will see a raft of it,” she said. “It is going to be coming before local boards, state boards and legislatures.”

A bill in Tennessee, backed by a leading Republican legislator, is expected to be the focus of heated debate in that state’s legislative session, which started this past week. The bill, introduced by Rep. Sheila Butt, seeks to exclude any “religious doctrine,” not just Islam, from middle-school textbooks.

Ms. Butt, an author of Christian books, said in an email that she wrote the bill after complaints from “constituents who realized that some religions were more heavily weighted in the standards and that doctrine was being taught to Junior High students.” Republican Gov. Bill Haslam has said the bill is too broad, but Candice McQueen, the state’s education commissioner, has sped up reviews of social-studies standards following the criticism.

Similar battles have gone before state education boards in Texas and Alabama, and there were calls throughout 2015 to revise textbooks in school districts in states including California, Wisconsin and Massachusetts. A group called Truth in Texas Textbooks Coalition won substantial changes—many of them regarding descriptions of Islam—from that state’s board of education in 2014, according to the group’s chairman, Roy White.

This past December, parents in rural Virginia complained when a high-school teacher assigned her students to practice Arabic writing by copying an Islamic statement of faith. Some in the community called for her to be fired, but others rallied to her defense.

At issue are books used in Pearson PLC’s seventh-grade curriculum “myWorld History & Geography: The Middle Ages to Exploration of the Americas,” used in 30 of Tennessee’s 140 school districts. For example, two pages on “Muslim Empires” state that Islam expanded through conquest but also “spread peacefully” in many areas and that “religious toleration” by Muslims toward Jews and Christians helped the empire expand.

Critics of the textbooks argue that Islam spread largely through violent conquest over the centuries.

“These textbooks present a promotional, positive view of Islam,” said Steve Gill, a spokesman for Citizens Against Islamic Indoctrination in Sparta, Tenn. He added, in light of recent attacks in California and Paris and in last summer’s incident in Tennessee, where a local Muslim man killed five members of the U.S. military, that teaching that Islam is “a religion of peace and tolerance is just not accurate now or in history.”

American Muslim groups say their religion is peaceful and disavow the recent attacks. “Like all people of faith, we completely reject any hateful ideology that would motivate violence between neighbors,” the American Muslim Advisory Council, a Muslim advocacy group in Nashville, said in a statement.

Such groups also say the textbooks being challenged give a generally balanced, if cursory, view of Islamic history.

“We all need more education about other faiths,” said Paul Galloway, of the council. Added Saleh Sbenaty, a council board member and an engineering professor at Middle Tennessee State University, “This is not Islamic indoctrination; it’s just teaching our kids history.”

In Tennessee, Muslims made up about 1% of adults in 2014, slightly more than the national average, according to the latest available data from the Pew Research Center.

Variations of the Pearson textbook are used across the country, according to company spokeswoman Laura Howe. “While we always are committed to presenting balanced, unbiased, and accurate material, we also are happy to meet with parents and listen to their concerns about textbook content,” she said in a statement.

Truth in Texas Textbooks also has critiqued a textbook from McGraw-Hill Education Global Holdings that the group said provided a misleading and inadequate explanation of “jihad,” an Islamic concept regarding fighting for the faith. A McGraw-Hill spokesman declined to comment.

David Cook, a religion professor and expert on Islamic history at Rice University in Houston, said Islamic governments in the past did force conversion in many instances. For example, the Ottoman Empire for several hundred years took Christian children from their families and forced them to become Muslim warriors.

Many Islamic regimes also taxed Jews and Christians for their faiths, he said, but “on the balance, Islam didn’t gain converts through coercion.” For example, Muslims took control of Egypt in the 600s C.E., yet Muslims didn’t become the majority in the country until hundreds of years later, he said.

Most major religions, including Christianity, at some point “used some sort of political or economic dominance to gain converts,” he said.