Then I flatten the bag so they will stack together nicely, and put them all in a container in the cupboard. The ten year old is trained to put his empty ziplock back in the container so we can fill it again next time.
When you're ready to cook it, just dump it into a bowl and add the liquid of your choice. I usually pour in some applesauce and add water until it's wet and some of the oatmeal is floating. (You might like to add milk, but our two year old is allergic to that so we stick with water). Then microwave it for one minute. Your microwave might vary, but that is the time that works for us. I always add fruit - sometimes raisins or craisins, sometimes banana, or chopped apples. I used to made it with strawberries until he became allergic to those. We are pretty limited to what we can put in because of his allergies, but you can add whatever you like - nuts or whatever.
I ended up with 20 packets, and I'll be lucky if that lasts us two weeks. I might need to find a bigger container so I can make more at once. :)