I am a bit behind in blogging about this. my apologies!
All 12 lessons can be viewed here
Week Two is shutter speed. The challenge is take the same photo on 3 different shutter speeds. The goal here is to demonstrate how to either freeze motion (high shutter speed) or blur motion (low shutter speed). Hence action shots (sports, animals, traffic) require a high shutter speed so you don't get that pesky "motion blur" where an arm, or tail or such is all blurry. but sometimes you want that really nifty motion blur, like in a river, or waterfall. That is when you would use a slow shutter speed.
In terms of everyday photos, a neat trick I was taught was to double your focal length, and that is generally what you should aim to keep your shutter speed at. Also, with kids, try to avoid dropping below 1/160, or 1/100 at a minimum.
So here is my photo challenge for shutter speed. A neighbour's fountain:
1/1000. See how the droplets are all nicely frozen in time? High shutter speed