Challenge Cards (Ideal for teaching ages 3 and older) Spark laughter and learning with fun card games! Match uppercase and lowercase letter pairs and build alphabet and reading skills. Whimsical illustrations provide letter sound/word cues. Versatile cards adapt to growing abilities for endless rounds of learning fun and mastery. Great for school, home, childcare, and travel. Durable, no-see-through cards. Quick-sorting rounded corners. 56 two-sided cards, 3 1/8″ x 5 1/4″.