In June 1966, The San Diego County Department of Education published a couple of Art Guides for classroom educators. A dear friend and retired teacher loaned me her copies to look at a few years back. They are of course out of print now, and I have no idea if you can get even get your hands on one. They are pretty fun and actually have relevant information related to art teaching.
Here is a lesson on Salt Dough:
With helpful hints:
Sand Casting which my friend used to do with her classes while on a field trip to the ocean. She had them use salt water to mix the plaster.
I did sand casting with fourth grade students in small groups a few years ago. We used shoe boxes to hold the sand.
Here are a couple of examples from my students:
Here they pressed plastic army men into the damp sand and removed before casting.
Here they added shells and glass beads and left them in to cast.