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.
See also these excellent demonstrations.
From Nrich comes an interactive Geoboard and a selection of problems to introduce circle theorems. As with all Nrich resources teachers’ notes are included. See these on the Subtended Angles problem for example.