I love using cards sorts in my classroom!
There always seem to be lively discussions about the topic, and I feel like this is a real benefit for students at all ability levels. Card sorts can really help students grasp concepts.
Recently, I used this cart sort about writing inequalities to solve word problems with my pre-algebra students.
What did I witness as I watched and listened as the kids worked? They did fairly well with matching the inequality to the word problem. However, they didn't understand how the "define the variable" step played into everything. Students were struggling to answer the question because they were ignoring what the variable was representing. They had to pay close attention to how the variable was defined in order to answer the question being asked. This was an "aha" moment for them and for me since I didn't expect that to be the challenging part of the task.
My takeaway from this activity? I need to give tasks like this more often so I can observe, listen, and learn. This is as important for teachers to do as it is for kids!
I've found some free card sorts online and have made others (see them at my TPT store). Here is a free one I love to use about matching a verbal description to a graph, and this absolute value inequalities card sort is an algebra favorite ... so helpful!