Indexes are not very sexy. They are also difficult to advocate for or promote in the K to 5 library. Nevertheless, they are a fundamental component of any library's reference section. I use indexes to locate information for my own professional development and so do my colleagues. As I have posted earlier, my K to 5 patrons have access to EBSCO.
I tried out a number of indexes from the UBC library and found them all quite good. The problem, as a number of other participants in LIBE 467 have pointed out, is the high number of spurious information a search can elicit. The need to identify and use appropriate subject terms is crucial. The best index for providing search suggestions is EBSCO's Academic Search Complete which has a subject thesaurus that gives subject terms suggestions based on your initial query. I wish such a powerful search feature were available for K to 5 students when using a tool like Searchasaurus.