What you'll need:
-7 1/2 cups of warm water
-3 1/3 cups powdered milk (this is a bit more than you would use to normally reconstitute the milk, but I've found it makes the yogurt a bit thicker and creamier. You could also just use 2 quarts(8 cups) of regular milk in place of the water and powdered milk)
-1/4 cup of store bought yogurt to use as a starter (or 1/2 cup of your own yogurt if you already make it yourself)

1.) Mix the water and powdered milk right in your crockpot and let it sit for a couple of minutes to completely dissolve.
2.)Turn the crockpot on low and leave it for about 2 1/2 hours. (This will bring the temp of the milk up to a point that it'll kill any bad bacteria.)
3.) Shut the crockpot off and unplug it. Leaving the lid on, let the yogurt sit for 3 hours (this brings the temp of the milk down enough that it won't kill the good bacteria in the yogurt.)
4.) Take 2 cups of warm milk out of your crockpot (I just dip in one of my clean, glass measuring cups) and mix in the 1/4 (or 1/2) cup of yogurt that you want to use for the starter. Mix with a wisk until completely blended (maybe a minute? Really easy and quick) and then pour the mixture back into your crockpot. Mix everything together, put the cover back on and then lay a quilt or thick towel over the crockpot for insulation (you want to keep it warm but not hot. Crockpot is still off and unplugged.) Now go to bed or walk away from it for the day! (6-8hrs)
5.) When you wake up, you'll have yogurt! Pour it into a clean jar or container (we try not to use any plastics anymore), cover and refrigerate. When it's nice and cool, it's ready to eat!

This is by far, the easiest and least expensive way I've found to make yogurt and it's come out sweet and creamy each time. My children love mixing jams, homemade granola etc. into the yogurt to make their own "flavor"!