Siman - Berachos Daf 16

• Workers in trees reciting Shema

Workers can say Shema while working up in trees since kavana is only required for the first passuk. They must come down for tefilla since it is a request for rachamim (mercy) and requires more kavana.

• Accepting condolences for slaves

Rabban Gamliel accepted condolences (מקבל תנחומים) when his servant Tavi  passed away because he was a talmid chochom, even though one generally does not accept condolences for a servant.

• A choson's exemption from Krias Shema

A choson is exempt from Krias Shema because he is preoccupied with the mitzva (טרדא דמצוה).