Once you have discussed and prepared how you will participate in the International Week of Prayer and Fasting, you can begin to think of how to make this accessible to children and give them a visual of the sacrifices they are making. A good way to do this is making spiritual bouquet posters.
There are several ways to do this, but I will discuss two versions.
The first is an actual bouquet of paper flowers glued onto a poster, like this one. You can find print outs of small flowers here and here. First have each person design a poster with green stems or a vase to be filled. The posters should then be hung in a common area for the whole family to view. Cut out various flower printables or make your own. Place the blank flowers in a small bowl or basket. Every time someone offers a prayer or sacrifice for the IWOPF, they then take a blank flower out of the basket, color it, label it with what they offered up, and glues it onto the poster. As the nice days progresses, the beauty of love, prayer, and sacrifices will be apparent through the blossoming bouquet for each family member.
The second version can be purchased as a download from Arma Dei: Equipping Catholic Families shop. This version involves adding petals to a flower center to create a flower of prayers.