Marking Scheme

The marking scheme should be in very simple language and concise. It will be read by TA's for marking and students for feedback. Any detailed or verbose information that is useful for marking but may be confusing for students should not be on the marking scheme. This information should be provided along with the solutions to the markers in each of their marking packages. Communicating with markers is vital for students to receive appropriate feedback and consistency across students grades.

Note that the information below assumes that you will be passing your marking scheme through a formatter before outputting it. If you are using BitterSuite, then it can format the marking scheme with nroff automatically. This suite also provides a convenient way to include totalled autotesting marks on the marking scheme automatically.

Formatting Notes

We control the level of indentation of the Marking Scheme layout using nroff command on a pre-prepared marking scheme file. The Marking TA's and students should have an easier time seeing how things line up if indentation is increased. This was done in the Winter 2009 term by changing the .in command to use an indent of -16 and making all of the .ti commands indent with multiples of 4 (4, 8, 12, 16). Here is an example:
.ad c
===================================================================
.br
Winter 2009 CS 136 Assignment 9
.br

Marked by :

.br

TOTAL       / 71
.br

===================================================================


.br
.ad l
.in 16
.ti -16

.br
.ti -16
______ / 22  -- Question 1

.br
.ti -12
compress.ss

.br
.ti -8
______ / 1 Correct Purpose (only for the main function)

.br
.ti -8
______ / 6 Efficiency

.br
.ti -4
______ / 1 O(n^2) or O(n log n)

Note that the question mark is flush to the left side of the page, with subcomponents of the question indented slightly so that it's clear how mark totalling should be done. Also, if any of the descriptions of how to give marks line-wrap, the indent on the following line will be much farther, making it clear the text is still part of the point on the line above, and not getting in the way of the column of totalled marks.

Also, the header lists the total mark and requires identification of the marker so there's an extra record of which TA marked which student.

Tests

Points for the test that the students wrote should be more detailed, doing tests in specific circumstances. Points for tests like this should be avoided:

(Copied from Assignment 6 marking scheme)

.br
.ti -4
______ / 2  At least 3 tests for add


.br
.ti -4
______ / 2  At least 3 tests for print_num

But instead more points for more detailed test should be provided:

(Copied from Assignment 9 marking scheme)

.br
.ti -4
______ / 1 At least 1 test for make_hash

.br
.ti -4
______ / 1 search with a item that is present in a hash table with 1 item

.br
.ti -4
______ / 1 search with a item that is present in a hash table with >1 item

Yet, there are some functions that only have 1 way of running (i.e having no if statements (for C) or no cond statements (for Scheme)) [such as the make_hash function above]; for those functions, can still just say how many test the students should have for it, but the number of tests that the students should at least then also should be just around 1-2, as there are only one way to run such function.

Notes

Notes should be provided in different parts of the marking scheme to provide more conditions or more information about the marking scheme.

For example:

.br
.ti -4
______ / 3  function first and rest

.br
.ti -2
______ / 2 Correct Purpose: one for first, one for rest

.br
.ti -2
______ / 1 Clear and readable code

.br
.ti -4
Note: 0/3 if student's codes does not handle the EMPTY case

In this example, it gave a condition on the three previous marks that need to be covered in order to get any of the three marks. In terms of the format, notice how before the note there is the:

.br
.ti -4

The .br refers to making a new line, if .br is not provided the note would be on the same line as the line "Clear and readable code" above. Also notice on how the tab works for the note, paring with the "/3" line and not with the other two lines. You should pair the note to the line that the note directly affects.

Also, if you have more than one note to put at the same location, those notes itself should also be separated by the .br tag.

While you can use notes to pose conditions, you can also use it to provide more information on a certain part of the marking scheme. For example, you could say something like: "Note: 5 points in the automarking is for the bonus delete function"

Cases

While it is not necessary for you to use it, you can use it in parts of the marking scheme where there would be partial marks on different answers (i.e Efficiency for codes). With cases, it would just have different case where a student submission would fit into, and that the student would only get marks for only one of the cases. This way, it would make giving partial less confusing.

For example:

.br
.ti -4
______ / 1 O(n^2) or lower

.br
.ti -4
______ / 3 O(n) or lower

In this situation, a student with a code running in O(n) should have 4 points, the markers might only think that it satifies the 3 marks for O(n) and not the 1 mark for O(n^2). This potential miscommunication can be taken care of by making it into a case:

.br
.ti -4
______ / 1 O(n^2)

.br
.ti -4
______ / 4 O(n) or lower

.br
.ti -6
Note: The students can only get marks for either one of the two cases, either 1/4 or 4/4.

This would make the partial mark giving more clear.

Alternatively, it should be possible to make this clear with only the test description (without the need for an extra note) by taking advantage of indenting:

.br
.ti -8
______ / 4 Run-time complexity

.br
.ti -4
______ / 4 O(n) or lower

.br
.ti -4
______ / 1 not O(n), but at worst O(n^2)
although wording needs to be careful still to avoid any markers now giving 5/4.

The need for extra notes

As the marking scheme would only have a short description of how the points are allocated, there should be extra pages along with the marking scheme to help out the grad TAs to know when to and when not to give students points or not. For more information on how to make the extra pages, check Communicating with markers

Topic revision: r9 - 2010-03-08 - TerryVaskor
 
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