Giant pieces of chalk await visitors at Walker Art Center, welcoming them to a fun and messy art experience. But there’s no chalkboard to scratch your nails on. Instead, the 64-inch-tall, 120-pound, human-sized pieces of chalk (and chunks from them) in the gallery are meant to be used for drawing on the floor or the walls, which have been treated with special chalk-friendly paint. It’s a funny thing, to get messy in a white-cube space where visitors are normally told to look, not touch, the artwork. Conceived by Puerto Rico-based collaborators Jennifer Allora and Guillermo Calzadilla, who have been working together since 1995, this traveling exhibition, simply called “Chalk,” has been touring the world since 1998. (11 a.m.-5 p.m. Tue.-Wed. & Sun.; 11 a.m.-9 p.m. Thu.; 11 a.m.-6 p.m. Fri.-Sat. through Feb. 2, 2020. Walker Art Center, 1750 Hennepin Av. S., Mpls. $7.50-$15; free for 17 and younger, and for all on Thursday evenings. 612-375-7600 or walkerart.org)