The Interval Cards provide extra reinforcement in reading 2nds and 3rds on the staff for: Preschoolers · Students with special needs · Review for any student. These cards can be used as a supplement to any method. There are 48 purple cards with a large-sized staff, including: 2nds · 3rds · Quarter Notes · Half Notes · All cards begin on the Landmark Notes of Treble G and Bass C. There are 48 green cards with a medium-sized staff. They are duplicates of the purple cards, in a smaller staff size, to allow students to play memory matching games and to become adept at reading staves in various sizes. There are 48 gray cards with a small-sized staff. This total of 144 cards provides plenty of reinforcement for reading 2nds and 3rds.