The index cards are Fontas and Pinnel's 100 high frequency words. My advice is to print them on colored card stock and laminate them. Then I separate the cards into piles of 10-15 and put them on rings. Students are given one set (one ring) and expected to practice them everyday. Once the student has "graduated" from that ring they can move on to the next. I have a star chart to go with this that shows how many times each student has graduated.