When I try to see if a person knows how to "think", I start with fizzbuzz and then ask them to do it again without if or case statements. The first time a person is asked something like that you see if they're a thinker or if they just go "that can't be done." That question does a good job dividing people into a group that in 5 years time will ether have 5 years of experience or 1 year of experience repeated 5 times.
