A free program for Android, by Family Locator.
You can find out where they are at any time. No need to check your phone every minute. This application is very easy to use. All you have to do is install the app and create an account.
With this app, you can also track your kids. You can check where they are at school and at home. If they are missing, you can also get a notification. It is a very easy-to-use app.
If they are running low on battery, you will receive an alert and be notified of their address. If they are driving unsafely, you will be notified and you can take steps to ensure they are aware of the dangers.
Family Locator can also be used for other purposes.