Check these links, for what really means to have the concept of "3rd Teacher" in your classroom:
1- A case study of remaking and redesigning a classroom and its effect on students.
2- http://www.thethirdteacher.com A book!
3- Making your environment your 3rd Teacher
4- Everyone can be a designer
5- Teacher's Blog on 3rd Teacher
6- "Entering the Third Space" article
7- Great Article on 3rd Teacher
8- What language does the environment speak?
9- A slide show for redesigning a classroom
10- A site that allows you and your students to build/create a virtual 3D model of your space before even building it!
