I redesigned these based off the free Plickers.com cards that are single-sided. The cards are scannable up to 20-25 feet away. My version adds a back-side that gives students a visual guide (arrows) for the ABCD answers to help with user errors (plus it shows the card # so students can easily identify which card is theirs. While this isn't a new concept, I also created them to be anti-cheat as the answer key on the back is small and a light shade of gray, making it really hard for anyone next to the student to see what answer they are showing.
PLEASE NOTE: This set is for a maximum of 30 students per class (you can use the same cards for multiple class periods).
You should print these in double-sided mode on cardstock paper. Be careful with regular school laminate as the glare can cause the scanner app to not always read the cards. I will be selling a physical version with matte (low gloss/low glare) laminate soon. I created my own special matte laminate set and they rock, so I wanted to get them out to the masses!