Have you looked into implementing Universal Design for Learning (UDL) or CAST? They're freely available and accessible to all. Here's a faq page for gifted and talented: (http://www.udlcenter.org/advocacy/faq_guides/gifted_talented). Here's another faq page for CAST: (http://www.cast.org/udl/faq/#q2)

UDL is not simply to help students master a specific body of knowledge or a specific set of skills, but to help them master learning itself. It is based on neuroscience and encompasses many fields and is thoroughly researched. There's information on critical thinking on UDL - including checkpoint 7.1 optimizing individual choice and autonomy! (http://www.udlcenter.org/aboutudl/udlguidelines).

Though UDL and CAST are aimed at those with print disabilities and special needs, UDL can help anyone "who plans lessons/units of study or develops curricula (goals, methods, materials, and assessments) to reduce barriers, as well as optimize levels of challenge and support, to meet the needs of all learners from the start. They can also help educators identify the barriers found in existing curricula."

Here's a link to UDL online modules:
http://udlonline.cast.org/home

Details for instructors (i.e. paradigm shift)
http://udlonline.cast.org/tdetails

And CAST online modules (including designing lessons/units)
http://cast.org/learningtools/index.html