Final answer:
The 'big idea' from the Magna Carta that influenced the U.S. Constitution is Limited Government, aimed at preventing an over-powerful central government and preserving the liberties of the people.
Step-by-step explanation:
The 'big idea' that the founding fathers took from the Magna Carta when writing the Constitution, which protects ordinary people from an over-powerful central/national government, is Limited Government. This concept ensures that the national government's powers are confined to those granted by the Constitution, preventing instances of abuse of power and maintaining basic liberties for the people. The framers of the Constitution implemented this principle by including a system of checks and balances and the Bill of Rights, which enumerates the specific limitations on the national government and the protections for individual rights, reflecting the influence of Enlightenment thinkers like John Locke and Baron Montesquieu.