1. Cut the top off and remove seeds from green peppers. Wash and set aside.
2. Combine beef, uncooked rice, oatmeal, onion, carrot, salt, and pepper in a large mixing bowl.
3. Stuff each pepper about 2/3 full.
4. Stand peppers side by side in the slow cooker.
5. Pour water in crockpot. Not over the peppers.
6. Pour tomato sauce evenly over the peppers.
7. Cook on low for 6-8 hours.
8. If desired, sprinkle cheese over the tops, place lid on crockpot and wait for 5 minutes for cheese to melt.