Your Challenge was to get a photo showing motion. It could be anything like your pet or kids, or traffic, or pedestrians.
To show the motion in your photo, you needed to slow down your Shutter Speed to a point where the subject becomes blurry. You had to be careful to keep your camera steady and not introduce camera shake.
Do you remember my photo of the stork flying in the Shutter Speed post. Here I was moving the camera with the flying bird to do the opposite.
Keeping the shutter open for too long - depending on your subject and artistic intent - can lead to some weird images.
The image of the girl running was shot at one-third of a second. Her fast movement - faster than I was expecting - resulted in a strange image where one of her legs has disappeared and there is a hole in her body.
If you leave the shutter open long enough, you can make people disappear completely, making the street look empty. Watch this video from DigitalRev where they shoot a street crossing and make most of the people disappear. Cool Long Exposure Photography Ideas
Here, same settings at a third of a second, but the subjects moving slower, resulting in a more natural image, except for the guy with three legs.