Reindeer poop (chocolate covered raisins) are a great hit with kiddies (there are a few different poems online to use).
Snowman soup (hot choc mix, candy cane as stirrer, few mini marshmallows too) is another one that you can also get nice poems and even printable bag toppers on the net.
Last year, I had DD (5), neighour (4) and other neighbour (8) helping me with a production line of Reindeer poops for DD's birthday treat for her class (all 27 of them - her birthday is 26th Dec, so we need something seasonal). First we measured exact amounts into small cello bags, then we folded over the bag tops and closed with sellotape, then we put on a topper using double sided tape that I had printed from the net with the poem on it. Worked great! And entertained the 3 girls on a wet Dec afternoon for an hour. I got the biggest bags of choc raisins I could get in healthfood shop, so not that expensive - I put a nice handful in each bag and only weighed to make sure they were even and I had enough to make it all around the class.
You could do a production line of Snowman soups too - the choc mix and candy cane are easily handled, counting out exactly 3/4 marshmallows for each is not overly taxing for littluns, and then you could control the folding and sealing if you need to.