MIUI 7 comes with a really useful feature for those of us with children, Child Mode.
Xiaomi’s Child Mode allows us to hand our phone to a kid, without having to worry that they will mess up any settings, or have access to anything they aren’t supposed to.
With Child Mode, you can blacklist and whitelist every app on your phone, and disable any app to send SMS.
Follow this step-by-step guide to enable Child Mode.
1. Open the Settings App
2. Select ‘Child Mode’ from the settings list
3. Turn on Child Mode, and toggle the SMS ability switch to how you want it.
4. Once you have made you choice for what apps are whitelisted, set a new pattern lock so only you can exit the phone out of Child Mode.Tap the home button to enter Child Mode.
5. To take your phone out of Child Mode, tap the X button, and enter the pattern you chose when setting up Child Mode.

All done! your phone is now out of Child Mode, and your settings have been saved for future use!
Enable Child Mode in MIUI 7 with this step-by-step guide | Xiaomi Ninja