I was thrilled when I found this method for making your own ice packs. So simple and if when he loses them, it won’t cost him his college savings to buy new ones. I buy the cheap pack of 4 sponges from the dollar store to make the loss-impact even less.
To make, just saturate a clean sponge with water and place into a ziplock bag. Lay flat in the freezer and freeze overnight. In the morning, just toss them into the lunch boxes. As they melt, they will reabsorb the water so just toss them back in the freezer after school!!!