This means I can see the work and her class' work and she can have access to mind.
It is very useful as you might see a resource you feel you could use with your class. As we are both teaching first years, it is very insightful to see what her students are producing.
The only inconvenient is with the free version of Seesaw you cannot add more than one teacher to the class so if you wanted to add a whole department you would have to go with the paid version.
Step 1 - go to class and click the wrench
Step 2 - click arrow on manage teacher