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Department of Computer Science and Technology


Marking Scheme and Classing Convention 2023-24.

This document is concerned with Part IA, Part IB, Part II and Part III Computer Science Tripos examinations, administered by the Department of Computer Science and Technology. 

Overview of the Examinations

The following table shows the components of the different Parts of the Computer Science Tripos (CST) and indicates the maximum mark available for each:

Examination Papers Assessed practical Maximum mark
Part IA 1, 2, 3 (+ NST Maths Papers 1 & 2) Assessed exercises 400
Part IB 4, 5, 6, 7 Assessed exercises 400
Part II 8, 9 and two Part II modules of assessment Project/Dissertation 400
Part III 5 Part III Modules Project/Dissertation 900

Each written paper and the Part II Project/Dissertation is marked out of 100. Each of the two Part II modules of assessment is marked out of 50. Part III modules of assessment are marked out of 100 and the Part III Project/Dissertation is equivalent to four modules. Details of the way credit is awarded for Assessed Exercises are given below.

Notes on Part IA

Every Part IA candidate offers Papers 1, 2 and 3 of the CST and the subject Mathematics of the Natural Sciences Tripos.

Every candidate is required to submit a number of assessed exercises. A satisfactorily completed exercise is awarded a tick. Details of the required ticks and all deadlines are specified each year by an announcement by the Head of Department.

There is an expectation that every student will pass all their ticks. The number and duration of ticks associated with a course is determined by the course lecturer(s) subject to oversight by the Tripos Management Committee. The guiding principle in deciding whether to use a tick should be whether it teaches a specific concept or reinforces important lecture material.

Mark penalties will be applied to act as a deterrent to missing a tick. The Part IA Examiners are supplied with a final tick list. Each missing tick will receive a penalty of 10 marks (10% of a paper). The maximum penalty is 100 marks (one full paper).

Notes on Part IB

Every Part IB candidate offers Papers 4 to 7 and is also required to submit a number of assessed exercises which are marked by the ‘Tick’ system, as for Part IA (above).

Marking Scheme for Parts IA, IB and II Written Papers

The 9 papers of the CST each contain between 8 and 14 questions and candidates are always asked to attempt 5 questions with 20 marks available per question.

Every question is based principally on material presented in a particular course of lectures and is normally set and marked by the lecturer who gave the relevant course.

Each question is heralded by the title of the most relevant course and the breakdown of the 20 available marks is clearly indicated. Each question is vetted by at least two internal examiners and, for Parts IB and II, the External Examiner. As a means of moderating the marking process, the External Examiner scrutinises a number of marked scripts selected at random.

Marking Scheme for Part IA and Part IB Assessed Exercises

Satisfactory solutions to the individual exercises are awarded ticks by those who are responsible for the associated practical classes. A submission has to pass a threshold of acceptability and the candidate may have to satisfy an assessor at a short interview (5 to 10 minutes). Unsatisfactory individual exercises which fail to obtain a tick may be resubmitted, subject to the specified deadlines.

Each Part IB candidate also takes part in a group project. Each member of each group must attend all the formal meetings and write a personal report. Each such report includes summary assessments of the contributions made by the other members of the group. The academic leaders of the group projects take these assessments into account when awarding ticks. No resubmission is possible for group projects.

Marking Scheme for Part II modules of assessment

Each Part II Module of Assessment will be assigned a mark out of a maximum possible 50 marks. During the year, provisional marks in the form of grades A-F will be determined on the basis of submitted coursework, practical exercises, written tests, and other elements as advertised in the announcement by the Head of Department, for the specific nature and content of that module. Provisional marks will be used as the basis for determining final scores, and these are out of 50 for each module.

Marking Scheme for Part II Dissertations

Every dissertation will have two initial marks. The first mark will come from unblinded marking by the marker* who will assess the dissertation with the help of the supervisor, such that the supervisor understands the reasoning for the mark proposed (and can later provide feedback to the student). The second mark will come from blinded marking by an internal examiner, who will not have access to any of the marker’s output prior to submitting their mark. The examiners will then reconcile the first and second marks to the final marks as they deem appropriate. If a significant mark change is chosen, the examiners will ensure that the marker is aware of the reasoning so that they can calibrate and update the supervisor.

*The marker is a senior member of the department associated with the project. The marker may also be the supervisor.

When all the dissertations have been read and marked, the raw marks are processed to produce a provisional mark. An order-of-merit table is drawn up and the examiners then discuss every dissertation in turn.

Candidates may be invited to a viva voce examination, at which additional expert assessors may participate. It is expected that in any year, around 5–10% of candidates will be examined by viva.

Classing Convention: Parts IA, IB and II

The scheme of weighting used to calculate the overall BA degree classification for CST is as follows:

  • Part IA - Zero, but students are required to pass the course in order to progress to Part IB.
  • Part IB - Zero, but students are required to pass the course in order to progress to Part II.
  • Part II – 100%, and the grade achieved in Part II will be the final overall degree classification.

There are three principal stages in classing Parts I and II of the CST:

  1. For each candidate, determine an overall total mark.
  2. Order the candidates by their overall marks, thereby deriving an order-of-merit table.
  3. Partition the order-of-merit table into classes.

Further details are given in the following sections.


In every written paper in the CST, candidates are asked to attempt five questions where each question is marked out of 20.

There is no scaling of total marks, or for individual questions in any part of the CST. However, the examiners may scale marks for individual questions in exceptional circumstances.

For Part IA and Part IB penalties are applied for any missing assessed exercises.


The aggregate mark for each candidate is used to determine an order-of-merit table. After discounting students who fail to be classed, the class boundaries are initially assigned by the Examiners in order to achieve at Part IA a partition of 25/55/12.5/7.5, at Part IB a partition of 32.5/52.5/10/5, and at Part II a partition of 40/50/7.5/2.5, for First/Upper Second/Lower Second/Third respectively. The final class boundaries are arrived at by careful consideration of those candidates who fall close to borderlines. For Part IB and Part II, this
procedure is overseen by the External Examiner. 

Examiners will use their judgement to decide which candidates shall be unclassed. In recent years this has been at a mark threshold of around 40%, which may be varied at the discretion of the Examiners, who will also take into account whether there is a significant gap in marks below the lowest classed candidate, or whether the candidate has otherwise not achieved a reasonable minimum standard for progression to the next part of the Tripos (for Part IA or Part IB) or to graduate with an Honours degree (for Part II). 

It is not the practice to scale the marks on individual questions. However, the Examiners reserve the right to apply such scaling if they see fit. The Examiners may additionally ask for questions to be remarked if they are not content with the mark distribution presented. In determining the final score for Part II modules of assessment, Examiners will take into account the need for fair comparison between different modules. 

In Part II distinctions will be awarded to any candidates who are placed in the top 10% of the classed candidates for both their dissertation and aggregate mark for the three written papers.

Classing Convention: Part III

Part III students obtain an overall percentage score for the year, with 60% being the passing grade, 67% being “pass with merit” and 75% corresponding to “pass with distinction”. The classification for Part III (the MEng degree) is obtained by the grade achieved at Part III only.

These scores are calculated by combining raw scores from individual modules with the score attained for the research project. Each of the five taught modules contributes 1/9th of the overall grade, while the project accounts for 4/9ths. In addition to attaining a passing grade overall, students are also expected to attain a passing grade for their research project.

In the process of Research Project selection, Part III students fix a Project Supervisor in conjunction with their Director of Studies. Because the Project Supervisor is an Assessor for the purposes of examining (i.e. provides a project mark), he or she must be a University Teaching Officer at the Department of Computer Science and Technology or otherwise approved by Head of Department.

The project dissertation is marked by one of the Part III Examiners or Senior Assessors, and by the Project Supervisor. Each assessor produces a percentage score, and these are averaged to provide a provisional mark. Should the individual scores be widely discrepant, a third assessor may be used. In addition, students may be called for a viva voce examination, which may lead to adjustment of the provisional mark.


Approved by Department of Computer Science and Technology Faculty Board (22/11/22), and published 23 November 2022

Updates approved by Department of Computer Science and Technology Faculty Board (17/01/23), and published 18 January 2023

Updates approved by Department of Computer Science and Technology Faculty Board (Feb 24), and published April 2024