I've just skimmed through this text, but it looks interesting. It uses case studies from both novice researchers (PhD students) and old pros to illustrate the challenges, opportunities and necessity of using theory to ground and interperet educational research.  The book is available as an e-text from Au library.

Applying Theory to Educational Research : An Introductory Approach with Case Studies
Adams, Jeff Cochrane, Matt Dunne, Linda 
Pages: 243 
Publisher: Wiley 
Location: Hoboken, NJ, USA 
Date Published: 10/2011