I usually begin with at least 5 lbs. of ground beef. I used approx. 5 lbs. of 90% lean ground beef for this tutorial. 

Non-food items needed:
Several baking sheets or pans with at least a slight lip on the edges (to contain the grease)
Good aluminum foil for covering baking sheets or pans
Medium ice cream scoop (with a scoop about the size of a walnut)
Quart-size freezer bags
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Recipe for 5 lbs. of meat (adapted from the 30 Day Gourmet cookbook:

Ingredients:

5 lbs. beef, pork, turkey - ground (any 1 or a mixture)
2 1/3 cup dry oats or cooked brown rice
1 3/4 cup diced onion
1 T + 1/2 t salt
1 3/4 t garlic powder
7 eggs
2 1/3 cup ketchup or tomato sauce

Heat oven to 375 degrees.

Cover all baking sheets/pans with foil. This will make it easier to clean up or reuse them)

Mix all ingredients very well either with your hands in a large bowl or in a stand-up mixer with a dough hook (divide ingredients in half and work half the recipe at a time if using the mixer). 

With the ice cream scoop, scoop the mixture and place in rows or circles (depending on the shapes of your pans) on the baking sheets/pans close together. 

Bake for 20-30 minutes. They should be lightly browned, not overcooked, and not pink in the center.

Cool and place in quart freezer bags. Label and freeze. The number you put in a bag depends on how many your family will eat per meal. I generally count 4 per adult, 3 per older child, and 1 per younger child or toddler. It also depends on the role the meatballs play in a meal; for instance, meatball sandwiches would require more meatballs than spaghetti and meatballs. Adjust as needed. 

We use these for:

Meatball sandwiches
Meatballs in gravy over egg noodles with peas
Spaghetti and meatballs

Here are 7 sauce ideas from the 30 Day Gourmet cookbook you can use with your meatballs:

1. Salisbury Sauce: One 10 3/4 oz. can cream of mushroom soup diluted with 1/4 cup water plus 2 t        Worcestershire sauce (or create your own white sauce).
2. Barbecue Sauce
3. Italian Sauce (Spaghetti Sauce)
4. Stroganoff Sauce (add sour cream to the Salisbury Sauce)
5. Teriyaki Sauce: 1/2 cup soy sauce, 2 t vinegar, 1/2 t ground ginger, 1/2 cup brown sugar, 2 t cooking oil, 1 minced garlic clove
6. Savory Sauce (good for meatball sandwiches): Two 10 3/4 oz. cans tomato soup (I sometimes sub tomato sauce), 2 t Worcestershire sauce, 1 1/4 cup water
7. Swedish Sauce: 5 T Worcestershire sauce. 2 T sugar, 1/3 cup water, 4 T any vinegar, 1 cup ketchup