Dear Mrs. Lyn,

This is certainly a good idea for children! But I thought perhaps I'd share a little more information about making butter.
I recently made butter the same way, except using a quart canning jar. It takes about 45 minutes for the butter to form. And as far as I know, it is very important to clean the butter afterwards, because it will quickly go rancid. Have you experimented with this? I would suggest that after the butter has formed, leave the lid on and place it in the frig for a while, maybe 20 minutes (NOT until it is fully chilled). Then take it out and drain off the buttermilk. Put the lump of butter on a plate and rinse it in ice water, while work it like dough. Once the water runs clear, the butter should be clean enough (it's the remaining buttermilk that makes it go rancid). You can then dry the butter off and refrigerate it.
We've had problems with leaving homemade butter out at room temperature, so at this point I'm not sure how well it will keep if it isn't refrigerated. Also, last time I tried to make butter, it simply refused to form a lump! I'm not sure what went wrong. But I plan on trying again later this week, and hopefully I'll be able to figure it out, and post what I learned.
Love,
Atlanta