Maybe you really can't measure 'grit' unless you put the student through several orthogonal tests and see how he does for the worst.
e.g. to determine whether the monkey or the fish has more
'grit', ask the monkey how deep it can dive into the ocean depths, and ask the fish how high a tree can it climb.
e.g. to determine whether the monkey or the fish has more 'grit', ask the monkey how deep it can dive into the ocean depths, and ask the fish how high a tree can it climb.