I've been researching for a concrete explanation about how we can classify the function of 'today' in "Today's topic" or 'today's activity'.
Someone corrected me with this sentence,
"Today's topic is about ' and 'You did a good job in today's activity.'
He told me that 'today' cannot own a topic or an activity, since apostrophe notes possession if not contraction.
How does 'today' function in the above sentences?