The Islamic State is teaching boys, some as young as 8 years old, how to behead "infidels." The Associated Press has a video report on the matter:

"The children were each given a doll and a sword. Then they were lined up, more than 120 of them, and given their next lesson by their Islamic State group instructors: Behead the doll. A former IS prisoner tells the Associated Press," the description of the video says.