The 13th, 14th, and 15th Amendments focused on giving past slaves rights, particularly voting rights.
Jim Crow laws and Black Codes were ways the Southern states responded to these Amendments, as they wanted to keep their way of life intact. Jim Crow laws were meant to segregate blacks and whites from each other. They essentially made it easier for the South to continue to treat African Americans harshly. The Black Codes were harsher and made it so black people could be arrested for basically no reason and they could not leave their jobs, even if they wanted to.
Poll taxes and literacy tests were more ways the South state responded. Poll taxes were put on voting polls, in order to stop African Americans from voting. Black people during this time had a hard time getting a job and were paid less, so many could not afford to pay for polling. Literacy tests were also very harsh on African Americans. Since many, did not and could not receive a proper education, they would fail the literacy tests and not be able to vote.
Critics of the Articles of Confederation argued that it was far too "weak" in the sense that it didn't give the federal government enough power over the states. This became especially evident after Shays' Rebellion, which proved very difficult to put down.
I just answered another of these questions, and the answer is The Bill of Rights.
