This is a great way to reuse a clean milk jug, and to save from using all those sandwich baggies. This is also a better alternative to store bought ones because it's not a big deal if one gets thrown away by accident. Make some now and be ready when school starts.
1-gallon milk jug
Adhesive-backed Velcro dot
Mark a clean 1-gallon milk jug.
Cut along the lines with scissors. To make the crease lines, use a thumbtack to pierce a row of dots at 1/4-inch intervals across each side of the jug, 1 3/4 inches up from the bottom. Fold the flaps at these dotted lines, then open them and fold them in the opposite direction along the lines (this will make the flaps easier for your kids to open and close). Fold up the box and add an adhesive-backed Velcro dot closure.