Pour 1/2- 2/3 c of any juice into a ziploc bag, Toss into the freezer.
Toss them into your child's lunch box in the morning and by

snack time or lunch time all they need to do is open the top

and insert a straw.
(My son gets a kick out of these, sometimes they are still

slushy at lunch and he calls them Slushbags.)

.