Public tongues and interpretation is a great activation to practice; it is thoroughly biblical and for some reason it isn’t something we do all the time around most churches. Paul gives us instruction of how tongues are supposed to work in public meetings in 1 Corinthians 14:

Public tongues require interpretation. When a public tongue is spoken out we should stop and wait for the interpretation.
Tongues are spoken to God, not to men. This means that interpretation should be directed to God and sound like prayer or praise, but not like prophecy.

To do the activation:

Ask God to come and release a public tongue. Many people will feel something in their mouth when they receive it, and when they do have them speak the tongue out over the group.
Pray and ask God to release the interpretation to the tongue. Wait until someone feels they have the interpretation. Most of the time it comes very similarly to prophecy.

I usually repeat this activation a few times and have the students observe what they are experiencing during the whole process. Often there is a powerful release in the Spirit with the interpretation of a tongue being delivered.