{Disclosure: Some links which follow are affiliate ones.}
The Devotion of the Three Hail Mary's
For the Devotion of the Three Hail Mary's we pray one Hail Mary in honor of each person of the Holy Trinity and ask our Our Lady to intercede for us with specific graces needed to live each and every day.
In a vision given to St. Mechtilde (sometimes called St. Matilda), the Blessed Mother described the devotion in these terms:
By the first Hail Mary, you will ask me in virtue of the supreme power which God the Father has given me to strengthen you in all your combats and to defend you against the power of the malignant enemy.
By the second Hail Mary, you will beseech me, through the admirable wisdom which I have received from my Son, to let the truth shine upon your soul and to banish from it the darkness of ignorance and error.
By the third Hail Mary, you will ask me by the burning fire of love with which the Holy Spirit has inflamed me, to give you such ardent charity as will enable you to overcome the fear and struggle of death.
St. Alphonsus, one of the greatest promoters of this devotion, recommended adding the following prayer at the end:
By thy pure and Immaculate Conception, O Mary, make my body pure and my soul holy.
Another option is to pray:
O my Mother, preserve me from mortal sin during this day (night).
Many also add a Consecration to the Blessed Trinity, and, you can even get a free printable prayer card from Catholic Tradition with the entire devotion written out that way.
How I Decided to Introduce the Devotion
As I said, I stumbled upon this devotion when preparing for a co-op class. Basically, I remembered a lovely little story called "A Box of Hail Mary's" from Angel Food for Boys & Girls (which you can also find read aloud for free on LibriVox in Angel Food For Jack and Jill: Little Talks to Little Folks).
Upon re-reading "A Box of Hail Mary's", I began to wonder if there was any significance to the woman in the story praying three Hail Mary's each morning and evening. Some quick research online brought me to information about the Devotion of the Three Hail Mary's, and, I thought, What a perfect way to celebrate Mary's birthday with the children! We can read this story and begin praying the devotion. Maybe we can even use a real box for them to "place" their Hail Mary's in as they pray them and this box can be placed in front of a statue of Our Lady as a gift when we sing Happy Birthday and enjoy cupcakes.
So, off I went to find a golden box in my home. Unfortunately, the one I thought I had was nowhere to be found, so, instead, I took gold scrapbook paper and made an origami box - making the top of the box with a full sheet of square paper and the bottom with a sheet that I cut into a slightly smaller square, so the box would have a base and top that fit easily together.
Then, during our co-op class, I read and chatted about the story and guided the children in making their own origami boxes (just bases without lids, though, due to time constraints), before we prayed three Hail Mary's and "placed" them in our boxes. The children were so cute as they carefully "placed" their gifts of Hail Mary's and, I hope, the boxes they made will remind them to pray the Devotion of the Hail Mary daily.