“Over, Under, Next: Experiments in Mixed Media, 1913–Present,” an exhibition of approximately 100 works drawn largely from the Hirshhorn Museum and Sculpture Garden’s collection, runs April 18 through Sept. 8. The first in a series of permanent collection-related exhibitions leading up to the museum’s 40th anniversary in 2014, “Over, Under, Next” surveys an era in which the definition and scope of art were continually expanded through the avant-garde’s embrace of “non-art” materials. Artists from virtually every major movement of the past century—from Cubism, Dada and Surrealism through Abstract Expressionism, Pop and Post-Modernism—participated in the revolution. The exhibition tracks the development of the elements of mixed media, from the wood grain-printed paper of Georges Braque to the beaded Easter baskets of Nick Cave. The roster of unorthodox and incongruous materials includes butterfly wings, glass shards, crumpled automotive metal, jigsaw puzzle pieces, clothing, furniture and colored sand.