Oct 31, 2018
Post: http://insideoutsidemichiana.blogspot.com/2017/02/books-on-boxes-for-loose-parts-play.html
October 6, Day of Play—Cardboard Challenge The date has changed a bit since 2012
https://cardboardchallenge.com/
Cardboard Challenge FB group: https://www.facebook.com/groups/618600058261581/
Article
Planning a Community Cardboard Challenge
; Bowie
Books on Cardboard as Loose Parts (aff links)
Christina Katerina and the Box