MDL-9376 changed the way the Q&A forum works by preventing students seeing other people posts until the maxediting time had elapsed (i.e. a typical 30 minute delay before students could see other peoples posts).

This was to prevent "cheating" where a student writes a quick nonsense post to peek at other peoples replies.

This reduces the functionality of the Q&A forum in the classroom context where they benefit from seeing the answers immediately.

I propose a new field in the forum settings form with a name such as Delay Display that controls if students can see others post immediately after they post a reply or after the system delay time.

I have experimented with the following modifications but have done minimal testing

It has been discussed at

https://moodle.org/mod/forum/discuss.php?d=219417

Add a new column to the forum table called delaydisplay of type tinyint(4) or equivalent.

Within the function definition() code in the forum mod_form.php file around line 59
(immediately after
$this->add_intro_editor(true, get_string('forumintro', 'forum'));
)
add the following code

$mform->addElement('advcheckbox', 'delaydisplay', get_string('delaydisplay','forum'));

$mform->addHelpButton('delaydisplay', 'delay', 'forum');

The en language file would contain

$string['delaydisplay'] = 'Delay Display';

$string['delay']="Delay Display";

$string['delay_help']='Delay Display yadda yadda';

To match the help button.

Modify the end of the forum_user_can_see_post method in
forum/lib.php code to read as follows

...

    if ($forum->type == 'qanda') {

        $firstpost = forum_get_firstpost_from_discussion($discussion->id);

        $userfirstpost = forum_get_user_posted_time($discussion->id, $user->id);

       $display=1;

       if($forum->delaydisplay==1){

        if((time() - $userfirstpost >= $CFG->maxeditingtime)){

            $display=0;

            }

       }

        return (($userfirstpost !== false &&  $display==1) ||

                $firstpost->id == $post->id || $post->userid == $user->id || $firstpost->userid == $user->id ||

                has_capability('mod/forum:viewqandawithoutposting', $modcontext, $user->id));

    }

    return true;

}