Rule reminder
Voi imperative = voi present tense (aprite!, scrivete!, finite!). Tu imperative: -are → present minus final -i (guarda!, ascolta!); -ere/-ire → same as tu present (scrivi!, apri!). Formal Lei: use subjunctive (scriva!, ascolti!).
The teacher says to the whole class: 'Open your books!' Which is correct?