If you have a custom question (multichoice) with more than one answer that is right, ie that has more than one answer with a score > 0
example:

• how many nails do mammals have on one foot?

• 1 (15)
• 2 (15)
• 3 (0)
• 4 (15)
• 5 (15)

• first weird behaviour:

• the total of that question is 15 but should be 60 (the answer is correct if you choos all of the items!)

• let select the first 2 answers

• the feedback is set to "wrong answer"
• you get 15 points out of 15

============= FIRST ISSUE ================
I understand the need of scaling the answers from one totally correct, down to totally wrong ones, as for

• Do mammals lay eggs?

• never (90)
• some peculiar species (100)
• yes (0)
  in which the right answer is the second but the first is almost right...
  This small sub-issue is resolved assigning a maxvalue to the question itself, and the score given for that question is min(question_max_value, useranswer_total_score) or just using multichoice-one answer only question type!

Comming back to the main first issue, it is resolved by changing the lines in /mod/lesson/locallib.php near line 1474
// Find the highest possible score per page to get our total
foreach ($answers as $answer) {
if(!isset($bestscores[$answer->pageid]))

{ $bestscores[$answer->pageid] = $answer->score; } else if ($bestscores[$answer->pageid] < $answer->score) { $bestscores[$answer->pageid] = $answer->score; }

}

in

// Find the highest possible score per page to get our total
foreach ($answers as $answer) {
if(!isset($bestscores[$answer->pageid]))

{ $bestscores[$answer->pageid] = 0; }

$bestscores[$answer->pageid] += $answer->score);
}

=========== SECOND ISSUE =========
The second issue should be resolved in file /mod/lesson/action/continue.php rewriting the logic of how the correctness is evaluated: in the example case, you got half the question right and no wrong answers!
It should be implemented as a tristate variable.

I did implement in another way:

• first set to false a flag for wrong answers ($wronguseranswer)!
• add a flag for incemplete answers that defaults to false ($missinganswers)
• in the check cycle set it to true if the user has sent a wrong answer
• on the final check reverse the filter (near line 313)
  if ((count($useranswers) == $ncorrect) and ($nhits == $ncorrect)) { $correctanswer = true; $response = $correctresponse; $newpageid = $correctpageid; }

  else

  { $response = $wrongresponse; $newpageid = $wrongpageid; }

  will then be

if($wronguseranswer)

{ // at least one useranswer is wrong $response = $wrongresponse; $newpageid = $wrongpageid; }

else {
// no wrong answers and the user has provided at least one answer
if ($nhits!= $ncorrect)

{ $missinganswers=true; }

$correctanswer = true;
$response = $correctresponse;
$newpageid = $correctpageid;
}

On the result page the user then shoul be presented with a third type of report: "Answer provided are correct but incomplete"

Hope this helps