You can reorder Lesson Items after you've added them to a Lesson. You can manually drag and drop the Lesson Item. You can also reorder Lessons in the same way.
Once you have a Course selected in the Courses and Groups dropdown menu, click the Lessons link in the Course Navigation bar.
Select Item to Move
Locate the Lesson item you wish to move.
Click the drag handle next to the Lesson item name. When in position to drag something, your cursor will appear as crossed arrows. Drag the Lesson item to the desired location.
Drop the item in the desired location by releasing the mouse. When in position to be dropped, Curve will create a gray box to indicate where the item will be placed.