Until recently, my puppy did not know how to behave on his leash. Enrolling him in puppy class was the smartest thing we ever did. First, he learned to come when his name was called. After that, he learned to stay in one place. Before long, he was the best-behaved dog in our neighborhood!What type of phrase is "enrolling him in puppy class"?What does "enrolling him in puppy class" add to the text?