(Definitions found at The Free Dictionary.)
Agenda: things to be done or a list of those things (as a list of the matters to be discussed at a meeting).
Diary: A daily record, especially a personal record of events, experiences, and observations; a journal.
Appointment book: a book containing a calendar and space to keep a record of appointments.
“Sandra checked her appointment book and saw the meeting, scheduled for 2 pm. She prepared the agenda, and included some topics she thought were important. Later that evening she wrote in her diary: ‘The meeting was a success!'”
Ainda está difícil de entender? Que tal uma aula?