Two days ago, we prayed through four of the Joyful Mysteries with our children and they did very, very well! Four is a new high for us. (The most we've every prayed is three.) Praying the Rosary with them seems to be getting easier every time. If you're currently trying to pray the Rosary with small children and are feeling discouraged, press on! It will get better and it is so worthwhile! For consolation: children are sponges and absorb way more than they appear to absorb.
We're probably progressing more slowly because we're using a "scriptural" rosary book rather than just praying the Hail Mary's end-to-end in the more typical way. I think this is a good approach. The little scriptural "thought" that precedes every Hail Mary teaches something about the Gospel Mystery, which is actually first exposure for my little ones, (unless you count the Mass, which is soaring right over their heads). The thoughts, and the pictures in the book provoke all kinds of questions. It seems like a perfect way to introduce small children to the Gospel.
We've also added the Canticle of Zechariah to our morning prayer routine. We are chanting it along with the Invitatory Psalm (95). Carol is not quite ready to sing with us, but when she is, we'll be ready to help her write all these Words on her heart. Chant seems like the perfect vehicle to train children in the faith who are by necessity an oral people, not a written people and the tones seem to be an excellent support for memorization. How many of us learned their ABC's to the melody of "Twinkle, Twinkle, Little Star" and still depend upon it!