Using Playing Cards

Today I was helping my mother get ready for a garage sale and saw that she was going to sell about a bajillion decks of playing cards. I thought, hmmm, these would be very inexpensive materials to use for games or responses in a classroom. Here are a few ideas (underdeveloped as I was just brainstorming):

• Hand each student or student-pair playing cards labeled 1-4. When asking students questions (multiple-choice), have students raise the corresponding playing card.
• Pick out cards that match. This is how students could be randomly paired (Red 2's, find each other, or for groups of 4, all 2's find each other).
• Use a modified version of the card game "war." Have students paired and both student flip up a card. The higher value card wins, but students quiz each other and can only take their winnings if question is answered correctly. If question is answered incorrectly, both cards can go in the kitty and the first person to answer a question correctly (on following turns) gets the kitty. (This might take preparation to have two question sheets prepared, with answers, to play. This could also take place in a group setting where group A and group B devise a sheet with questions and answers and the pairs to play war consist of one student from group A and one from group B)
• Each student can take a playing card as they enter, teacher can randomize responses by asking the student with the four of diamonds or the jack of spades (etc.) to respond or reflect on class material.

I'm sure there are many more options to think about in terms of the use of playing cards. Please add your comments if you have had success with playing cards in the classroom or if you have any additional ideas that might be exciting to try!