A panel for use in a drop ceiling system, or with appropriate modification, a wall, wherein the ceiling system includes stringers and cross-members defining areas therebetween for support of the panels wherein the panels include at least one planar sheet of material secured to a reinforcement member having channels formed therein to extend in at least one direction relative to the sheet material. When more than one sheet of material is used, the sheets of material are disposed on opposite sides of the reinforcement member. The panels are flexible for easy insertion into the openings between the stringers and cross-members of the support system and are readily compressed into a thinner profile for shipping purposes.