How are checks and balances a part of federalism?
It is not really accurate to say that checks and balances are a part of federalism. Instead, it would be more accurate to say that federalism can be seen as one kind of check or balance.
Checks and balances are powers that the three branches of the federal government have over one another. They allow each branch to prevent the others from doing anything excessively questionable. This is a way of preventing any one part of government from becoming too powerful.
Federalism also helps prevent any one part of government from becoming too powerful. It prevents both the state governments and the federal government from getting too much power. It does this by dividing the power between them. In this way, federalism can be seen as a check or balance.