The recepie is almost the same. Usually, teachers make play-dough by themselves, try to avoid mess in the class-room; but this is great opportunity for children to feel themselves self-confident, creative and responsible.
This is a recepie: There is the process
P.S. This dough called in Russia "Salted dough" or "Russian porcelaine" and many artists use it to create wonderful souvenirs.
A few years ago, before I came to Canada, I and my children with their friend gathered together to create ormanents for Christmas Tree. We dried it, painted with paint and decorated with glitter. There is a secret for modeling you have to exchange woter for potato starch glue( 1+1/2 tea spoon potato starch mix well with 1 cup boiled water and boil it for 1 min. Cool down)
Here they are And here some which we made for Christmas 4 years ago with Canadian children 4 and 6 years old