For those who, like me, can't wait an official public release for a fix when asking little Sally about classroom activities I figured a quick (and dirty?) bypass...
Here we go...
To bypass the crash during Sally's conversation about class activities, you must when option "Class Activities" is visible (but before trying it

) :
1) gain control in renpy console (see below if you can't enable console)
2) type in console the two lines below
goals.open_block("act1_ch5_class_activities") <Enter>
goals.open("act1_ch5_class_activities", 1) <Enter>
<Escape> to leave console
Now it doesn't crash anymore and all seems to be ok (I'ven"t yet finished the game...)
Time doesn't change as Sally says but there is nothing in code to change it
Changes made to enable console :
1)In \renpy\common\00console.rpy change config.console = False to True (don't forget to delete 00.console.rpyc)
2)In \game\modules\nondeveloper\main.rpym change
config.console = False to True
config.keymap["console"] = [] to ['shift_O', 'alt_shift_K_o']
delete (or comment) the line _console.console = None
(don't forget to delete main.rpyc if present)
Have a good game