I have found that children just absorb the scriptures, with no effort. I would read a Psalm to the children before bed. After 2 nights, they would be filling in the last word of each verse. Within a week, they would know them. Just choose a passage ad repeat it often.
There is also a great CD available from
www.nogreaterjoy.org. It is called Bible ABC's. It has a scripture for each letter of the alphabet and it is sung and then the chapter and verse are sung as well. It is such an easy way to teach children 26 verses of the Bible.