The textbooks are titled “English for the Islamic State.”

Iraqi troops found them at an orphanage when they liberated eastern Mosul in February.

They are unlike other textbooks most people grew up with. The courses in reading, writing and arithmetic are also an introduction to war, jihadism and terrorism.

In the alphabet, “B” is for battle, “G” for gun – with a picture of an AK-47.

The letter “S” is for sniper, with a picture of, presumably, an ISIS fighter aiming his rifle. The letter “W”, or woman, shows an indiscernible black figure – presumably a burqa-clad female.

And then there are the pictures of AK-47s and bombs used for math exercises.

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While many people have seen videos of the so-called “cubs of the caliphate” executing people by shooting them in the head or cutting their throats, these textbooks illustrate ISIS’ indoctrination and brainwashing of children from an early age, when they should be watching cartoons instead of executions.

The orphanage where the school books were found was used to groom children to become ISIS child fighters or informants, according to Iraqi military officials.

Ruth Feldman, a child psychologist at Bar-Ilan University in Tel Aviv who has counseled children traumatized by war and terrorism, said the toxic education of these so-called “cubs of the caliphate” only stokes the distress of living in a harsh environment, making them easy prey.

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“This makes their brain very open, very susceptible to propaganda and influence,” Feldman told Fox News. “So if you read implicit or explicit messages like in these textbooks that someone is responsible for this distress they live in, they will hate that person.”

The UK-based Syrian Observatory for Human Rights estimates that at least 300 ISIS “cubs of the caliphate” were killed in the first two weeks of the battle to re-take Mosul. The fighting began in October of last year and continues today.

The NGO “Save the Children” estimates that more than a million children who have been living under ISIS in Iraq have been either forced out of school or forced to follow the terror group’s perverse curriculum – a training course that, in the more advanced levels, trains students how to make suicide bombs and carry out successful beheading techniques.

“Those messages in the textbook help them divide the world in two,” Feldman said. “We are the just one, the right one. They are the enemy, they are wrong, they are hateful and need to be killed. And this is how children grow up on violence and hatred.”

John Huddy is a Jerusalem-based foreign correspondent for Fox

News.