A collection of excellent free resources for demonstrating the various circle theorems:
Tim Devereux has created GeoGebra applets which allow exploration of the circle theorems. You can access each theorem from the menu on the left which includes a useful summary of all the theorems.
Jane Hart, the founder of the Centre for Learning and Performance Technologieshas for the last five years has been generating an annual “Top 100 Tools for Learning” list by asking learning professionals to share their favorite tools for learning.
Looking at the list – as a teacher I use many of these tools; I thought I would outline here those tools in the list I use in my Mathematics teaching. Each link takes you directly to the site or to a post giving further examples of the use of that tool.