In middle school in California, our music class teacher showed us what I thought was a little strange way to play the castanets. He had the one shell mounted on a board. I think there must have been a little block to raise the shell a little off the board so it would resonate. The upper shell was fastened on with rubber bands or springs so it was hinged open about 20 degrees. Then he whapped on the upper shell with both hands like playing bongo drums to give the same fast clackety the Spanish ladies do with one hand.

He was slightly apologetic about this, but pointed out that what those ladies do is beyond normal human abilities so he did it this way. He was in the symphony orchestra and they didn't have a goal to feature a lady dancing around waving her arms; just to make the sounds.

I might add that on another day he played a movie reel of something or other, so the lights had to be turned off, and granted there would be some unrest among the students in the dark, when he saw projectiles arcing thru the beam of the projector he with his high cultural sensibilities felt he had to stop the film and chastize whoever threw it.