Flashcards with a divisor of 2. I've included a 2nd page that has the answers. It can be printed front to back for student practice or you can choose to just print the 1st page. It would work better on thicker paper (card stock or construction paper) but I made the answers a little lighter so it can't be seen through the page as easily.
I found on our printer, I had to choose to flip the page on the short edge so you may need to experiment a little to get it just right.