The categories answer different questions. "Expressed" identifies the textual source, "implied" describes a means of executing granted authority, and "reserved" identifies power left outside the federal grant. "Concurrent" describes overlap, not a separate constitutional source. Taxation can be concurrent even though each level taxes under its own authority.

Start with the actor and action. Congress must connect regulation to an enumerated power; a state ordinarily relies on its general police power. If both rules are valid, ask whether compliance with both is possible or federal law displaces the state rule. The Tenth Amendment does not reverse the Supremacy Clause.

A useful answer names one category and explains why it fits. Congress coining money is expressed; creating a national bank to carry fiscal powers into execution is implied; state health regulation is generally reserved; and both levels may levy taxes. Do not treat "federal" as proof of supremacy until federal authority is established.

Video lesson: Federalism: Crash Course Government and Politics #4