Paint: Make Paper Poinsettia
Cook: Mexican Wedding Cookies
Also read:
Zetta the Poinsettia by Alma Hammond
The Night of Las Posadas by Tomie dePaola
Las Posadas: An Hispanic Christmas Celebration by Diane Hoyt-Goldsmith
If you would like to participate and enjoy this celebration, there is wonderful music and play book for you available. I found a video showing more about one version here. The video is mostly in Spanish, but the book comes in English too.
Carlos, Light the Farolito by Jean Ciavonne (I was unable to find a read aloud for this, if you do please let me know)
Uno dos tres posada (Uno Dos Tres Posada: Let's Celebrate Christmas) by Virginia L Kroll