Facebook is currently rolling out a new passphrase feature to its Messenger Kids app, allowing children to send and accept friend requests on their own. Before anyone freaks out, it's important to note that both sets of parents still need to approve the connection.
The way it works is that Facebook will generate a random four-letter password for each child. This password is then shown to the other kid who enters it into his or her own app. Both parents then receive the notification that their offspring want to connect, and they must approve it.
This feature is opt-in and disabled by default. The goal is to make it easier to use at its core, i.e. communication and connecting with each other, while maintaining an element of security for the 13 and under chat app. Again, both parents have to be aware of and approve the friend requests between the two children (without the adults having to be friends on Facebook themselves), and they can still monitor the messages at their discretion.
Passphrases are rolling out starting today.