How do I go to the home screen while on the phone in iOS 10?

In previous versions of the iOS, I was able to go back to the home screen in the middle of a phone call. This is helpful, when you need to check email, get an address, or look something up on the calendar while talking with someone. Since the iOS 10 update, I cannot seem to locate the button to get back to the home screen. I have an iPhone 6 - 16 GB running iOS 10.1.1 (14B150) on the T-Mobile network.