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The ritual the O.P. is describing is a typical blessing of ordinary objects, of which there are many examples in the Shorter Roman Ritual, for example. (Keep in mind that there is no set “rite” for blessings of this kind—the ritual is indicative, not binding.)
The blessing of a “normal” object does not turn it into a sacramental or (better said) a sacred object. Only an object destined to specifically religious use becomes a sacred object. (I am not aware of any specific Church law regarding this, but this is clearly how the rites of blessings treat such objects.)
Such a blessing (i.e., of school supplies) is not really intended to increase one’s chances of passing an exam (I am afraid that there is no substitute for studying), but rather reflects the fact that even “mundane” goods such as these are, ultimately, given to us by God. It is a way of giving thanks to Him, and of placing potentially difficult circumstances (e.g., exams) into His hands.