This study first defines prior knowledge as theme knowledge which means directly related knowledge about a given subject, and intends to analyze prior knowledge effects on reading comprehension ability and written expression ability of children at risk with learning disabilities. The results were following. First, the tested group exhibited better performances statistically against the post test for reading comprehension ability than the other. Second, the tested group exhibited better performances statistically against the post test for written comprehension ability than other. In sum, prior knowledge has the positive effects on reading comprehension ability and written expression ability of children at-risk with learning disabilities. Therefore, it suggests that prior knowledge must be an effectual method to improve the deficiency of the children.
Key words : prior knowledge, learning disability, reading comprehension, written expression