Final answer:
George encourages Lennie to play with Slim’s puppies in the barn unsupervised to keep him out of trouble while satisfying his love for soft things.
Step-by-step explanation:
On page 63 of Of Mice and Men by John Steinbeck, George encourages Lennie to play with Slim’s puppies in the barn unsupervised. This instruction comes as part of George's ongoing efforts to look out for Lennie and keep him out of trouble. He sees this as an opportunity for Lennie to engage in a safe activity that satisfies his desire to pet soft things without the risk of Lennie inadvertently causing trouble or harm due to his lack of understanding and physical strength.