Here's an easy way to use pattern blocks in your classroom: simply print out a set for each student onto card stock, cut out the patterns or tangrams and presto! You're ready for some patterning exercises. Need some ideas for patterning activities? Try the 2nd and 3rd links below; the last one also includes some tangram pattern sheets for your students to model.
Oh - and don't forget! You get the full-size tangrams or pattern blocks if you click on the link, and not the picture.