Part 4, however, starts us all over again. Nothing in Part 4 has any relationship at all with Parts 1, 2, or 3. However, Part 4 is absolutely essential for Part 5. Part 6 will come along at the end of the semester and tie together Part 5 and Part 1, so the first half of the course and the last half will reconnect toward the end of the semester.
If you have struggled at all in Parts 1,2, or 3, then Part 4 offers a fresh start.