Keeping it short and simple today.
O Mary, conceived without sin, pray for us who have recourse to thee.
Here is the same prayer that St. Maximilian Kolbe added to:
O Mary, conceived without sin, pray for us who have recourse to thee, and for those who do not have recourse to thee, especially the enemies of the Church and those recommended to thee. Amen.
for more information about the Miraculous Medal and St. Catherine Laboure check out these web sites:
This second one has some nice coloring pages and activities for children and families.