Some people. They're just stupid.
Lets clear this out.
.mdl = Model. They go in half-life/mod/models.
.spr = Sprite. They go in half-life/mod/sprites/.
.wav = Sound.. They go in half-life/mod/sound/subdir (Possibly).
.bsp = Binary Space Partition. Or, in this case, map. They go in half-life/mod/maps/.
Please, learn how to spell.
Please capitalize properly and use punctuation.
Please, use proper grammar.
Please, don't abbreviate words that aren't supposed to be abbreviated.