The first grade teachers at school absolutely love introducing subtraction and addition number sentences to their kids using the book Ten Flashing Fireflies by Philemon Sturges.  I discovered this book in a lesson recorded in a Math Solutions book entitled Minilessons for Math Practice K-2.  There is also a similar lesson (I think…not positive) in another Math Solutions book entitled Teaching Arithmetic.  In the lesson students model the action of gathering fireflies into a jar using snap cubes.  In the book there is a jar  printable to use  or the lesson suggests using a sheet of blue construction paper to represent the night sky.  Not only is this lesson good for introducing the action of subtraction and addition, but it is also good for discussing one more and one less.  Because this is such a beloved book that builds a great foundation for addition and subtraction, I worked on building this free SMART Board lesson to accompany the book this weekend, and so here is an example of this lesson.  Just click to download the SMART Board lesson for free.