How to make a self watering container out of bottles

Here's a fun DIY project to do with kids. It's easy requires few supplies and works great for indoor our outdoor use.
Supplies:
Empty bottle (water bottles work well, as do larger 1 liter soda bottles)
Scissors
knife
Duct tape
Cotton ball
Potting soil
Starter plant ( long root plants work well, you want to select something that won't outgrow its container too quickly so herbs and lettuces are best)
Have fun!