CineCalidad. Know the Letters is a powerful instrument designed to teach the alphabet to infants and toddlers for an opportune period of time when they begin to speak. A recent study of more than 50 infants and children who watched "Know the Letters" daily resulted in most children gaining full recognition of upper and lowercase letters by the end of two months. Many of them learned in less than two weeks. You will be amazed at how easily your little ones can learn letters!