The children had been studying colour words with their regular teacher. Stealing an activity idea from one of my pre-service teacher candidates at the university where I teach, I decided to print out big bubble colour words, and give each student some playdough to make into the letters of the word. (So for "red", the child would have to roll some "snakes" and make an R, an E and a D, and then press them onto the page, into the outline provided.)
20 minutes later, we were enveloped by playdough. It was everywhere, on the floor, smushed into the table, bits in hair, on shoes... OMG!!! Two of the girls had made beautiful little playdough snakes and obligingly formed them into the letters for "green" and "red", but the rest of the kids had fashioned some kind of bulbous mess with their playdough, jamming it onto the pages in big mounds before proudly coming to show me their creations!
Miraculously, we managed to get it all tidied before the end of the period (though I did swing by the custodian's office to apologise in advance for the inevitability that he would find some stay playdough smushed into the carpet or elswhere later on). Overall, it was a fun activity, and some of them started to develop an awareness of the shape of some letters, but I think I would do a little more modelling ("here's how you roll a playdough snake, boys and girls") before I attempt something like this again!