There are many ways to use model drawing, even in a first grade classroom! My little monsters LOVE model drawing! It just makes sense in their brains! It's super fun to watch them problem solve using model drawing throughout the year.
Some great resources for model drawing are:
http://www.crystalspringsbooks.com/index.html?stocknumber=402624 (I would highly recommend purchasing this book if you have an interest in using model drawing in your classroom! The solution key, offered separately(http://www.crystalspringsbooks.com/402623.html), is super helpful if model drawing is a new to you).
There are some free problems to work here: http://www.sde.com/success-systems/wordproblems.asp
And solutions from prior offered problems here: http://www.sde.com/images07/ss/pdfs/Solutions6-13-11.pdf