We have been making flash cards for a long time, more than 25 years, and we know what teachers like: Notched corners for quick organization Bold, heavy type to use with large groups Large, easy to handle 6-1/4" x 3-1/4" (16cm x 8cm) cards Self-checking Durable, thick card stock (14pt.) Classroom sets that have all of the facts Sturdy set-up boxes. Titles in this series: BASIC FRACTIONS FLASH CARDS, ADVANCED FRACTIONS FLASH CARDS