Khan Academy on a Stick : Why we do the same thing to both sides: simple equations

Khan Academy on a Stick

The why of algebra

Why we do the same thing to both sides: simple equations
Representing a relationship with a simple equation
One-Step Equation Intuition
Adding and subtracting the same thing from both sides
Intuition why we divide both sides
Why we do the same thing to both sides: two-step equations
Why we do the same thing to both sides: multi-step equations
Why we do the same thing to both sides basic systems

If the above player doesn't work, you can try this direct link.