On Walmart.com where you can now buy this
18-Piece Rubbermaid Brilliance Leak-Proof BPA Food Storage Container Set for only $19.98 (regularly $29.98).

This would be great for back to school lunches, to take to the office, or even to pack after school snacks for the kids to grab themselves!
This food storage set is guaranteed not to leak, as the containers are BPA-free, built with an airtight leak-proof seal and secure latches, and have crystal-clear lids and bases that make it easy to see what’s inside. They are stain and odor-resistant, and have built-in vents that allow steam to escape so you can conveniently microwave food without removing the lid. Plus their modular design stacks perfectly in your fridge or lunch bag, helping you save space.