[LON-CAPA-users] questions about our first exam - partial marks

[Joseph Mingrone]

Hello,

I've been asked to write an exam and I'm struggling with the request to
assign students partial marks under certain conditions.

The first condition is based on the number of tries the student takes to
get the correct answer.  For example, if the student gets the correct
answer on the second try (after a hint has been displayed) we would like
to give her half the weight of the question.  Maybe the custom response
problem is the way to go?  Maybe we're trying to force a square block
into a round hole?  If you've done this, example code would be great.
I've seen the post below, but the solution isn't clear to me.
http://mail.lon-capa.org/pipermail/lon-capa-users/2012-August/004127.html

The second condition is for an Option Response with a foil group.  The
professor would like to assign 0.5 for each correct option chosen and
-0.5 for each incorrect option chosen.

After reading the author manual, this is my best guess.

  <part id="assumptions">
    <parameter name="maxtries" id="75" type="int_pos" default="1" description="Maximum Number of Tries" />
    <parameter name="problemstatus" id="78" type="string_problemstatus" default="answer" description="Show Problem Status" />	
    <startouttext />(g) Indicate the correct statements<endouttext />
    <customresponse>
      <optionresponse max="6" id="80" randomize="no" TeXlayout="horizontal">
	<foilgroup checkboxvalue="True" options="('True','False')" noprompt="1" checkboxoptions="nochoice">
	  <foil location="bottom" value="True" name="foil-ev">
	    <parameter name="weight" id="94" type="float_pos" default="0.5" description="Weight" />
            <startouttext />Statement 1<endouttext />
	  </foil>
	  <foil location="bottom" value="False" name="foil-es">
            <startouttext />Statement 2<endouttext />
	  </foil>
	  <foil location="bottom" value="False" name="foil-n8">
            <startouttext />Statement 3<endouttext />
	  </foil>
	  <foil location="bottom" value="True" name="foil-nd">
            <startouttext />Statement 3<endouttext />
	  </foil>
	</foilgroup>
      </optionresponse>
      <answer type="loncapa/perl">
       ### code here to check the indices of $$submission and add .5 for
    each correct option chosen and subtract 0.5 for each incorrect option chosen... ###
	return(ASSIGNED_SCORE,0.3);
      </answer>
    </customresponse>
  </part>

Thanks for any tips,

Joseph