Topics worth teaching re. public speaking:
1. How to structure a persuasive narrative,
2. Techniques for focusing on the material you intend to present (minimizing internal distractions),
3. Techniques for dealing with potential distractions externally,
4. How to evaluate your performance objectively (long time to master, but should be introduced early),
5. How to organize your material so that you have an appropriate amount prepared for the time allotted,
6. How to pace your delivery so that you deliver material in a consistent amount of time,
7. Techniques of rhetoric so that you can convey through your performance the emotion you intend (an inspirational speech is as much about how something was said as what, for example),
8. etc.
Topics worth teaching re. team work:
1. How to read the level of engagement of other members.
2. How to read the mood of other members.
3. How to be communicate clearly to a group and make sure that you were clearly understood.
4. etc.
I could keep going but I'm not developing a course for public speaking or intra-personal communication (teamwork). I could easily find as many topics for teamwork as I did for speaking.
All of these things must be developed with practice, sure, but a lot of them don't just spontaneously develop without teaching. I mean, I have been in plenty of group environments among adults who haven't learned these things. We send people to counseling over some of these issues. Practice is only useful if it is mindful: if the students know what they are trying to do. I could throw a ball on an empty field and tell my kids to practice soccer, but they'll learn a lot faster if they receive coaching with their practice.