One of the books we bought was this little book, for my nieces (also available online).
I think it's the best children's Mass book I've seen - it has spaces for the child to write or draw in what the readings are about each week and who and what they're praying for, and is wipe-clean so that it can be used again and again. It has the full text of each of the prayers which are said by the congregation, so that a child who is beginning to read can join in.
But the best bit is that there's no dumbing-down. Here's what it says about the Consecration:
"The priest remembers what Jesus said and did at his Last Supper. He says and does the same...
I will hear a bell at this part of the Mass as it is so important. When the bell rings I will look up at the bread. It is now Jesus, the Bread of Life. Then I will look up at the wine. It is now Jesus, the Cup of Salvation...
The bread and wine have been changed into Jesus. This is the great mystery which we believe in. To show our belief we say one of these prayers."
And at Communion:
"We go to the altar and receive Jesus, the Food and Drink of Life.
Jesus, this is a very special time for us. I love you Jesus. I enjoy this quiet time. I will talk to you in my heart...
The priest and altar servers clear away everything that was used for the Holy Meal. The altar is empty now, but the people in Church are filled with God's special gift of Jesus.
Jesus is with us and we are the Body of Christ."
And then there's the positive message at the end of Mass:
"At the end of Mass there may be a hymn to sing. I will join in joyfully, just as I would at a party.
Mass has ended, but it has made us strong for our work and play during the week.
Thank you for making me kind and loving through this Holy Mass."
The book encourages the child to sit still and listen to the readings, to listen to the Homily or, if the priest is "talking to the grown-ups", to think about the Gospel and imagine he was there. It encourages the child to join in the responses with the congregation and also to say his own prayers at various points throughout the Mass.
Rather than distract the child to stop him from playing up, it explains to him what's going on and involves him in the prayer of the whole community.
My only regret is that we only bought one copy...