It would be a relatively simple logic test - they'd have to identify a range of logical fallacies that are commonly used in arguments. Straw-man, Slippery-slope, False Dilemma, Proof by Association, and so on. It is very important to teach all children how to spot logical fallacies, because politicians love to use them (We must bomb this nation, or we will be unsafe! We must ban this technology, or the world will be destroyed! We can't let X happen because Y will INEVITABLY FOLLOW! My opponent supports Z but did you know, that HITLER once supported Z?)
They would be presented with a collection of 70 logical fallacies, presented in argument form and they must pin-point the fallacy. It would be a simple test of logic - you wouldn't have to know any facts, you'd only have to pay attention to the phrasing of the argument. As long as kids were taught about logical fallacies before the test was undertaken, they'd have no problem passing the test.