Index flow can be found in the Page Designer in the Flow tab. Choose Index Flow.
Why make an Index?
An index is a very easy way for parents to find their children in the yearbook. With an index, it's not necessary to search every page of the yearbook to find one student. The index also allows parents to find the photos that they may not have known their child appeared in.
What is Index Flow?
Index flow is a way to automatically create an index of all the people featured in your yearbook. The index is sorted alphabetically and specifies each page the person appears on.