Why not teach them the old standard on the oatmeal box meatloaf. It's decent, easy, they've grown up with it. It's useful, they can always resurrect it later in life by buying a box of oatmeal.
Then show them options and how to be versatile. How to take the recipe and change it.
Add a can of ortega chilies and tomatoes, a little cumin, build the loaf around a cheese center. Serve with a spanish rice.
Add Oregano, basil and parsley. Maybe some fennel. Use a marinara for the sauce with parmesan and a side of pasta.
Chopped bell peppers and green olives = pimento loaf.
Saute carrots, celery, mushrooms, tomatoes, add to the meat mixture. Show them how to take the dripping from the meat loaf and make a gravy.
Get them to take the recipe and think about altering it with ground turkey and pork; and how they could season it. Poultry spice, onion and celery, Can of mushroom soup with dried cranberries.
Open their eyes to spice and flavor groups; and the basic principle of a meatloaf ................ how to clean out the refrigerator by making one.