The Greek word for "instruct" or "teach" is katecheo. Katecheo is where we get our word "catechize." A Christian catechism is an organized teaching tool meant for the instruction and discipleship of believers both young and old. It is usually accomplished through the memorization of question and answers.
The goal behind this catechism is two-fold. First, Paul says he would rather speak five words for the instruction of others than ten thousand words in a tongue (1 Cor. 14:19). A crucial and central aspect of Christian discipleship is teaching (Matt. 28:19) and catechisms are a helpful and accessible tool to use in this process. Second, Moses calls Israelite households to instruct their children in the Shema (Deut. 6:7-4). It is my sincere conviction that catechisms are the best way to pass Christian theology and biblical truth on to the next generation.