Add the milk, tapioca pearls, sugar, and salt to the bowl of your large slow cooker. Stir. Cook on low for about 3 1/2 hours, or on high for about 2. When it's done the tapioca will be swollen and soft and the pudding will have the consistency of heavy cream. It thickens as it cools. Stir in the vanilla. Keep the lid off and let it cool for about an hour. Transfer to a covered container to chill overnight.
http://www.yourveganmom.com/your_vegan_mom/2011/12/crock-pot-tapioca-and-the-art-of-cookbook-pairing.html