This experiment is such a fun experiment, because kids of all ages have so much fun doing it! I did this experiment with my preschoolers before and they loved it. Like Emily said, having the kids wear gloves is a really good idea because the bags do get very cold. Also, I would suggest double bagging when it comes to the shaking part, because the bags will get holes or rip due to the crazy shaking of it. You will need a good amount of ice inside the bag, so you definitley want to over compensate for the ice part because you don't want to run out or not have enough. Also, the salt is a very important part and you don't want to run out of that either so I would make sure you have enough salt for all of the kids. One of my students was loctose intolerant so we used soy milk for his icecream and it tasted the same and he loved it! I think the cool thing about this experiment is that you can follow the measurements for the ingredients, but you can add more of anything and the experiment will still work, so theres a lot of trial and error room in the experiment, which can be a great learning experience for the students!