The O Antiphons are a beautiful prayer for the seven days before Christmas (starting December 17th) that tell of each of Christ's seven Messianic titles based on Old Testament scripture: O Sapienta (Wisdom), O Adonai (Lord and Ruler), O Radix Jesse (Root of Jesse), O Clavis David (Key of David), O Oriens (Dawn of the East), O Rex Gentium (King of the Gentiles, and O Emmanuel (God with Us). The images are a nice way to illustrate the prayers though absolutely not necessary to begin the O Antiphons this year! Some easy ideas would be to print larger images to hang on the wall, to make paper ornaments, to view a picture on the computer as you say the prayer. Add the song O Come, O Come Emmanuel (see link below for the appropriate verse) - sing it or play it for those who are tune-challenged, as I can be!
I could copy all the prayers for you, but you can find a beautiful spread at Family in Feast and Feria to print and use that I found last year. Take time to read the post as well. I believe it is well worth checking out. She also has other suggestions in bringing the meaning of the O Antiphons to children such as through song, food, and symbols.
This is an easy tradition to add to your Advent season, and one that draws you back into the season of preparation, as it is so easy to become side-tracked this close to Christmas (I know I do!).