There are several tutoring programs, or reading intervention programs, that have received research support and empirical support as being very effective in teaching children to learn how to read. Most of the programs that teach the alphabetic principle, the correspondence with the letters and their sounds, such as the Orten-Gillingham approach or the Lindamood-Bell, have shown to be very effective in helping children to read. As children get older, there are other programs that may focus on other aspects of reading, such as reading comprehension. Those are speech or language based programs that help to build vocabulary, help to increase the child's knowledge of grammar, and syntax, as well, inferring meaning from the written material.