Michele,
How wonderful that your children are so open to learn about God. Be encouraged! <img src="/forum/images/graemlins/joy.gif" alt="" /> You might want to start with a simple Children's Catechism.
http://www.grace.org.uk/faith/childcat.html
This is the paedo version, but is nearly identical to Baptist beliefs except the Baptist version would refer to Baptism and the Lord's supper as ordinances, not sacraments. You should have no problem using it.