Can someone please summarize for an 8th grader? this is the supreme court case marbury v. Madison

When it comes to conflicts, someone has to make the final decision. The writers of the Constitution did not determine which of the three branches of government would be the final arbiter, or decision maker, on constitutional issues. Today, it is assumed that the courts are the final authority on such matters. However, their role wasn’t always clear.
In 1803, the U. S. Supreme Court case Marbury v. Madison established that the Supreme Court has the power to determine whether or not the actions of the other two branches of government are legal and in line with the U. S. Constitution. This is called judicial review.
In his last days in office, President John Adams appointed several federal judges and justices of the peace, including William Marbury as Justice of the Peace for Washington D. C. Some of these presidential appointments were not finished before the end of the Adams presidency. President Thomas Jefferson told his Secretary of State, James Madison, not to deliver the unfinished letters of appointment because Adams was no longer President. William Marbury said that there was an act of Congress that required Madison to make sure that Marbury got his appointment as justice of the peace.
The Supreme Court ruled in Marbury’s favor, but said that a section of the act of Congress Marbury mentioned was unconstitutional. The Court also said it had the power of judicial review, the power to decide whether certain laws and government actions are unconstitutional.
With the power of judicial review, the Supreme Court became the chief interpreter of the U. S. Constitution. It also made the judicial branch an equal branch to the legislative and executive branches. With the power of judicial review, the judicial branch can check the actions of the legislative and executive branches and made sure their actions are in line with the Constitution.
Since Marbury v. Madison, the U. S. Supreme Court has relied on the power of judicial review to make sure that government actions are constitutional. Historians say that Marbury v. Madison influenced the Court’s decisions in Brown v. Board of Education and Bush v. Gore; and other issues that have an impact on daily life.