Arthur has a recent video about this on YouTube, Boogie Woogie Left Hand - from ZERO to INDEPENDENT in 15 exercises. https://www.youtube.com/watch?v=lfvCrwHWmkU It is very inspiring and gives ideas on how to occupy the right hand while practicing the left hand. It gave me a 16th idea for an exercise. I have a bowl of coins for my right hand to play with. There are endless things you could do with the coins; stack them, count them, pick them up one or two or three at a time, separate them by type as in pennies, nickles, dimes, etc. I have been using this exercise and some of Arthur's from the video for three days and I am making progress in training my brain towards hand independence.