(1) PHP OO Class 1: General overview of the concept of inheritance in object orientated programming.
(2) PHP OO Class 2: Class visibility and inheritance.
(3) PHP OO Class 3: Encapsulation.
An excellent (ultra important I'd say) example on object oriented programming in general (not just the concept of Encapsulation).
(4) PHP OO Class 4: Visibility and Inheritance by Example
(5) PHP OO Class 5: Inheritance and the final keyword
(6) PHP OO Class 6: Inheritance review
(7) PHP OO Class 7: Abstract classes and Interfaces
Great resource: http://www.youtube.com/user/dordrak
