Here is what I did:
1 cup old fashioned oatmeal (not instant)
4 cups water
In a crock pot add a little bit of foil to the bottom of the crock. You want to crinkle it some. The point of the foil is that you don't want to have the inside bowl directly touching the bottom of the crock pot. You want to use a bowl (I used a 4 cup liquid measure) that will fit inside your crock pot with room on the sides. To the bowl add the water and oatmeal. Place bowl inside of the crock pot. Add water to the crock pot bowl making sure you don't put any water into your oatmeal bowl. Add enough water until the water is to about the same height as the oatmeal water line. Cover the crock pot with lid and turn the crock pot onto low. Do all of this just before you go to bed, that way you will have oatmeal when you wake the next morning.
Here is what the cooked oatmeal looks like in the crock pot.
The bowl I used was okay but the oatmeal come right to the top so try to use a bowl that is a little larger than 4 cups. Also, the next time I make this I will use steel cut oatmeal instead of the old fashioned. The old fashioned oatmeal came out a little mushy for my taste and I think the steel cut will have a little more texture.
Spoon the oatmeal into a bowl and add whatever toppings you like. I added brown sugar, dried cranberries and pecans.