I understand 99% of what Pamela explained, but have a problem with ONE single analogy.

The Little kid walking 4 sidwalk-blocks per second, and then the builders adding sidewalk-blocks between him and the school....

She is adding him to the blocks.

BUT... that wouldn't make him go faster toward school. It would slow him from the perspective of the school. He would have 4 times as far to go if the sidewalk blocks were added in front of him even though he was still moving at the same speed.

A better analogy would be walking on a static mover, like at a theme-park and the people are walking 1 MPH on the mover, but the mover is moving at 1mph. So the person covers twice the distance in the same amount of time.