Some for play and some for eating.
Our grandson loved these "worms" from the National Wildlife Federation's Be Out There website, and they're a healthy-enough treat that we didn't have to feel guilty serving them.
This is much better than the commercial variety. It has a better texture, it doesn't have any toxic ingredients, and it's always available in a few minutes.
Of course, it wouldn't be good to eat so much salt, so we gave it to our children and grandchildren only when they were old enough to know not to eat it or when supervised.
This dough lasts a long time when stored in a plastic bag.
NOTE: It will look really soupy and lumpy until the last minute when it becomes thick. It's hard to believe that it will become dough, but it does!
Stored in a plastic bag, this keeps several weeks.