Heat a skillet over medium heat, and add the ground beef, 3 teaspoons water, chili powder, cumin, oregano, paprika and salt. Stir well to combine, and cook the mixture for 2 minutes, then remove from the skillet. Place in an insulated food storage container to keep warm, or store in the refrigerator until ready to serve, and heat in microwave for 1 minute before placing in thermos.
Place the lettuce, tomatoes and avocado in lunch box storage containers. Place the cheese and tortilla chips in separate containers. Make sure one of the containers is large enough to serve as the mixing and serving bowl.
Pack the containers in an insulated lunch box, along with a fork.
Make recipe as above, or let kids choose their own DIY ingredients from the following lists: protein (instead of ground beef, try ground turkey, shredded chicken, crumbled tofu or beans); whole grains (instead of tortillas chips try cooked brown or white rice or cooked quinoa); vegetables (instead of lettuce and tomatoes choose chopped sweet bell peppers, chopped cucumber, cooked corn kernels and/or chopped jicama); toppings (instead of cheese and avocado choose Greek yogurt, chopped black olives, ranch dressing, pepitas or salsa).