I used to do a lot of group activities in my classroom (2-4 students per group). I had 8 student groups in my old classroom and this meant creating 8 sets of a single activity (or sometimes 16 sets if I wanted a group of four to split into pairs). I didn't mind creating all the sets because the management of smaller groups was easier than working with a large group. However, at the end of the school day, no matter how hard I worked to get the students to keep their sets separated, there was always a set or two with extra cards. I would waste precious nap (or grading) time going through all the sets. I realized I needed a method to quickly identify mixed sets.
What I am sharing with you is cheap and easy. There are multiple ways you can tag your sets to quickly identify them. Keep in mind that you should tag your cards with an identifier prior to lamination (if you like to laminate). This will ensure that the identifier is sealed...well, of course, if students don't tear the lamination off.
I used the circular stickers for this tutorial. You can find them at most office supply stores or even your local grocery store.
For each set, place a sticker (or use a marker to draw shapes or lines) on the back of each card. Do this prior to lamination. Below you can see that I placed 4 pink stickers on the back of each card of one of the sets. Additionally, I am also showing how you could use a marker to scribble, color, or draw on the back of each card instead (especially if you don't want to spend money on buying stickers).
Remember, you will need to use a different color sticker or other identifier (e.g. marker) per set. Laminate once you have placed different identifiers on each set.
The picture below shows that I have 8 sets (of the same activity) - all with a different identifier. Note: I just used one card from each set to show this in the picture.
Finally, place each set of cards in a baggie or container. I prefer to use Ziploc baggies because they are cheap and last a long time. Additionally, you can stuff a bunch of card activities into a drawer or closet. If using stickers, I also recommend placing a matching sticker on the bag. This will help students catch cards that don't belong to a set (especially if you ask students to conduct a quick check prior to return). For example, only cards labeled with a blue sticker should be placed into the blue baggie and so forth. Of course, you could buy colored baggies to be even more organized; however, this should work if you're on a budget.
I hope this helps keep your cards/activities a bit more organized. This tip will come in handy if you utilize task cards in your classroom.