Use pattern blocks to visually represent math problems in addition and subtraction. To model number sentences, you need a piece of paper to use as a work mat, a pencil and pattern blocks that have been sorted into shapes.
Addition Number Sentences

Choose two shapes such as green triangles and orange squares. In the center of the work mat, leaving plenty of space for the pattern blocks, write "Triangles + Squares =". Then, count out some triangles and place them above the triangle spot. Next, count out some squares and place them in the square space. Write the number of triangles and squares under the shapes. Count how many squares and triangles that you have altogether and write the total number after the equals sign.
Subtraction Number Sentences

Use pattern blocks to model subtraction in two ways, take away and difference. To model take away, prepare your work mat by writing "Triangles  Triangles =". Count out a number of triangles, place them above the first space and write the number of triangles beneath the shapes. Then, take away a portion of the triangles. Write this number down, count the total remaining and write that number after the equals sign. Next, model difference by choosing two different shapes. Write "Squares  Triangles =" on the work mat. Choose more squares than triangles and write the number of each shape on the work mat. Line up the shapes next to each other and count how many more squares than triangles there are. This is the answer to the subtraction problem.
References
 Photo Credit Wavebreakmedia Ltd/Wavebreak Media/Getty Images