hardboard/pine is always a good alternate to save weight, mdf is just what i like to use, for a wall like that 1/2 would be fine
1/8" hardboard is pretty sturdy stuff, as long as you frame it right with the pine, it would easily hold bookbags and stuff like that with out bowing
1/8" hardboard is pretty sturdy stuff, as long as you frame it right with the pine, it would easily hold bookbags and stuff like that with out bowing