I just finished this lesson and what to talk about my miserable fail so that the next person can learn from my mistakes.
First, I did this with a group of 20 rowdy 3rd & 4th graders (maybe that was my first mistake, but I'm not going to count that).
My three main problems: There was not enough ice (2 5k bags = enough for max 10 students)
There was not enough salt (1K salt = enough for max 10 students)
I didn't buy the 'easy zip' bags. I bought regular ziplock bags.
It was quite warm in my room and the ice started melting almost immediatly. Bags busted, the outer ziplock leaked, and water got on everything. Only 1 or 2 students actually got close to ice cream consistancy. The rest had a mess and a frown. We ran out of wipes and the desks, floors, and chairs were too wet to sit on.
I do plan to do this activity again, knowing better how much of each item I need. Plus, my next attempt will be with 5th & 6th graders. Much more able to follow directions. I think this is a great activity, just not well executed on my part. Also, I think this would be better outside because the bags do make quite a bit of condensation if the ice melts.
Happy creaming.