The 5 Views of the iPhone 5 Calendar App
You have to rotate the iPhone to its side to examine your weekly calendar. In this view, you can glance at only five days' worth of entries (fewer on the 4 or 4s), so you must scroll in either direction to peek at any days that are not initially visible. The current day is circled in red. You can arrange to start your weekly view on any day of the week. Tap Settings→Mail, Contacts, Calendars→Start Week On, and then tap the day on which you want to start your week.