The average child uses over 500 plastic baggies in one year for school lunches. 500! A reusable set of snack bags can easily replace those 500 bags going into our landfills every year. $16 for a set of my machine washable zippered bags (one small, one large) is a bargain to save that much plastic from being thrown away.
Proper washing (cold water) and line drying will extend the life of the bag. We are using bags which are on their third school year.
The zipper closure mimics the plastic version, is easier for children to manipulate open, plus it doesn't pick up laundry lint like a Velcro closure would. You can find these in local shops like Clements Market, at my artisan fair booth, or let me know what fabric you would like directly and I am happy to make them for you and/or your children. Making a bag in a fabric you adore is one way to ensure that it will be used often!
These are available in two different sizes and two different linings. The standard bag has a ripstop nylon lining which is food safe, water resistant, machine washable and great for items such as crackers and non-messy sandwiches ($7 and $9). The second version is lined with PUL, a waterproof material which is also food safe, machine washable and great for messier or "wetter" snacks like PB&J or freshly-washed grapes ($10 and $12). Keep in mind that the bag overall is not waterproof--you cannot throw this bag overboard and have it protect your phone--the zipper itself is still somewhat porous.
Even if you don't buy your reusable bags from me, it's worth considering alternatives to plastic baggies.
Knitters are the best! I knit badly, but I love to sew lovely bags to keep their projects, needles and hooks in order. I also teach sewing, and you can find many sewing resources here. Welcome to my blog Dancing Threads RI.