Being able to quickly group your students is very helpful as a teacher. I have three quick and (mostly) free ways to group them.
This first set of grouping cards I use when I want to pair my students up. I found these free grouping cards on Teachers Pay Teachers from Making it as a Middle School Teacher and I love them!
Another great way to group kids is by using cut up paint swatches, and the students have to find the other colors in their "family". I got this idea from Fast Times of a Middle School Math Teacher, and headed straight for Home Depot. I asked the lady in the paint section if I could take a few cards, and she let me take as many as I wanted (I only took 8: pink, red, orange, yellow, green, blue, purple, and gray - of course I picked the cards that most closely matched my classroom colors, because I'm a little neurotic...)
The third easy grouping idea is to use a regular deck of cards. I bought a new deck for $1 at Walmart. What I love about playing cards, is you can split the class in half (red vs black), into four groups (each suit is its own group), you can group by fours (all kings, all queens, etc), and so on. There are tons of different ways to group using playing cards.
How do you group your students?