B.R.
It might be a little large, but maybe she could use it all day. I bought my daughter a thermos made y "Thermos",' it has a flip top that flips open with the touch of one button, the straw/drink tube is under the cap and flips right up, they don't even have to touch it with dirty hands and it is kept clean under the cap when not in use.(and it's BPS free) It is very well insulated and stays cold all day, and even overnight when we have forgotten it in the car. I bought it for my daughter in 1st grade because K was the sickest year of her life and all that I could attribute it to was the water fountains at her school. What about ziplock bags for sammwichs, veggies, etc?
http://shopthermos.com/products/lunch_kits/funtainer_lunc...
They make food containers too that are great for hot food like Mac & cheese, pasta, etc.. Good luck! (if the link above doesn't work, google thermos funtainers)