For history we've been reading about Samuel Finley Breese Morse who made a workable telegraph and invented the Morse code. So, of course, we had to give it a try. I remember doing the same thing when I was homeschooled as a missionary kid.
We got our instructions from here.
And, yes, it worked! Until we moved it upstairs to communicate from room to room.
Oh, well. Back to the drawing board.
It was a lot of fun and good activity.