ISIS is on the run in Iraq and Syria, but it has left behind a generation of child soldiers brainwashed and trained to kill.

CBS News correspondent Charlie D'Agata, reporting from Iraq for "CBSN On Assignment," saw just how the terror group turned children toward violence.

A former journalist showed D'Agata English textbooks that ISIS used to indoctrinate kids as young as 5.

D'Agata, right, reporting from Iraq CBS News

"They are teaching and brainwashing each other with these books: 'I can shoot.' 'Yes you can.' 'He can bomb," the journalist read from a lesson.

"This is crazy here," D'Agata said, pointing to another page. It contained a lesson for telling time.

A lesson for telling time in an ISIS textbook CBS News

"You know how to tell the time in English, but rather than just having a regular clock it's a time bomb, it's a timer on a bomb," D'Agata said.

The book was used for first graders.

"Children of ISIS" will feature in the premiere of "CBSN: On Assignment" – a new primetime documentary series which first airs Monday, July 31, 2017, (10 p.m. ET/PT) on the CBS Television Network and on CBSN, the network's 24/7 streaming news service.