Chalk Talk. A throwback to the days when convincing the already convinced was entertaining and a bit nuts. As you will see by watching this clip of the master at work, one Peter S. Ruckman. To be fair, he does more than speak in tongues, but if you are interested, other clips of him at work will be seen by those who seek.
Chalk Talk for Young People J. W. Van De Venter No date (1900?) 96 pages
Chalk Talk Made Easy William Allen Bixler 1932 128 pages
Both Collection Jim Linderman