On May 4, 2009, Pope Benedict XVI addressed some 4500 children, ages 8 to 13, at the Third Missionary Encounter in Spain. The Holy Father "[invited] kids as young as 8 years old 'enthusiastically speak about Jesus' so as to bring the light of the Gospel to those who do not know [Christ]." and to "'grow in friendship with Jesus, the friend who never fails through prayer and the sacraments, so as to speak of him with enthusiasm to those who have perhaps not had the joy of knowing him.'"
For more on Pope Benedict's address to kids, go to http://www.zenit.org/article-25779?l=english