Joe McIntosh writes a blog devoted to gifted kids with resources for teachers and parents. Here's a link to one of his articles on differentiating instruction for gifted learners. He has many more there.
Don't forget to use the teacher's editions of your textbooks as a source of material for differentation. Each chapter usually includes ways to extend the lessons for gifted students (as well as ways to provide additional learning support for struggling students).
For journal writing resources try the Thinkfinity portal, which has access to some of the best lesson plan databases on the net:
The National Association for Gifted Children is a wonderful resource. Here are a couple of links. One link is an article that was on their website which I found well written and comprehensive. The other link is the main home page for NAGC. Enjoy!
M.A. of Ed in Teaching and Learning
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