Hi SgtTJCallhoun
Although it may seem sensible to ask the teacher, your hestitation to do so speaks volumes and that instinct may be correct. I certainly have asked innocent questions only to have the teacher take it totally the wrong way & be exceedingly bristly/ defensive thereafter.
My advice (given to me by some incredibly sensible parents here on MN) is go out there and encourage your DD to discover great reading materials herself. Read the school books, but if it's too easy and she's basically mastered it, move on to other things. Whether this is open or kept quiet is entirely up to you - we opted for writing it down and recording it so the school knew and gradually other children saw this and did similar - it resulted in books being changed at least 1x a week and in some cases 2x a week - which really livened things up for everybody.
Obviously the library is a great first port of call for finding out what's out there and exploring.
Don't be bashful - use the opportunity of a trip into town to the shoe store to also visit the big book shop and let her browse. I've discovered both DDs have certain preferences and one is a sucker for an exciting cover illustration. Often they are totally aware of what friends are reading and want to read it too!
Some great websites to get ideas are:
Book Trust: Book Finder for children (if you don't go directly there with this link - look at list on left - book finder is usually right under children's books: www.booktrust.org.uk/books-and-reading/children/)
How to build a children's library - Guardian list of children's books: www.guardian.co.uk/books/series/building-a-children-s-library - books for 8-11 is a bit hidden - but is an option there. 0 - 3 and 4-7 are prominently displayed.
Richard and Judy Children's reads (www.richardandjudy.co.uk/childrens-current-reads/Autumn-2012/229) - with archive lists toward the bottom here www.richardandjudy.co.uk/current-reads-archive- has introduced us to some books I never heard about before: in 2010 (sadly that archive is not listed) we were introduced to Rudica the Rude (a hilarioius story of a little Celtic girl coping with the Roman colinisation of Britain). There's several in the series now (which I'm considering buying in for summer reading fun even though DD1).
I think a nice mix of genres is important - especially as both my DDs have very strong likes (DD1 adventure stories & DD2 anything princess) - but buying things like national geographic junior magazines or magazines related to TV shows can get them reading outside that. We've also found children's encyclopaedias (My first Question and Answer's Book, etc...) really useful.
Finally when you're out and about over the summer holidays - if you're visiting a historic property (English Heritage/ National Trust) or Museum take a peak at the gift shop - often there are educational colouring/ activity books - which are great for reading and a lot of fun.
HTH