Are teachers wearing masks while teaching or is it mainly the students?

Yes, the teachers are wearing masks. They're the ones most at risk, after all. Young people are much less at risk from COVID. Someone I know who teaches in New York posted today that the NY schools are going back in session because they've found that, contrary to expectations, the students are very good about wearing masks and staying distant, and schools are not the source of the outbreaks we are now seeing.

Some teachers have clear face shields so students can see their mouths. Where I am, school is still virtual, so the teachers are alone in their classrooms, teaching online, and don't need to wear masks. 

I have a feeling it depends on where you are located; I know where I am in Oregon, if you are in a space without a barrier EVEN if you are 6+ feet apart, everyone in that space has to wear a mask. Then again, most counties are still 100% distance learning. 

Biden says EVERYBODY must wear masks,

Mandatory Maskshttps://www.youtube.com/watch?v=o6-5A8K5r7gCarpent... Dust masks work well keeping saw dust out of the lungs. But are worthless regarding a virus.Unexplained is that MASKS are to protect the OTHER person, not you.Sneeze/Cough can project particulars around FIFTEEN FEET, uncovered.Social distancing is a "Feel Good" at Six Feet. Worthless for unmasked people.Any covering for a face will reduce the "spread" from ONE foot to Zero.

Masks protect others, not the wearer.