This project gets the most compliments (by far!) when on display in the halls. My guess is because of the quality of chalk and the overall success that is had by students. I did this project last year exactly the same way... for the original, more detailed, post check it out here.
This is one of the ones that floats all over Pinterest in the winter so unfortunately I cannot take any credit for it. And if you have not read the Snowmen series by Caralyn and Mark Buehner, you do not know what you are missing!
For our project and purpose of talking about shadows we read and observed the illustrations in Snowmen at Night.
I can statement: I can add shadows and shading correctly to a snowman using chalk.