Several points of fail, both from the kid & the instructor.
But I disagree that ensuring the gun was not loaded is one of them.
A gun sitting on a table is perfectly safe & doesn't need to be unloaded.
Instructor:
did not teach firearm safety
did not demonstrate firearm safety
allowed / told kid to handle rifle with people downrange
did not stay close enough to control what the kid was doing with the rifle
Kid:
treating a gun like a toy
ignoring rules 1, 2, & 3
instructor asked the boy to take the rifle in his hands, without making sure that the weapon at this point was not loaded
And ignoring the fact that there were people downrange.
the child apparently jokingly took aim at the people in front of him, and pulled the trigger, fatally hitting the family friend in the head and killing him instantly
An example of ignoring all 3 rules at once, and what can happen when you do.