Make students mark

April 20, 2001

When students assess one another's practical work, they gain insight into the material while staff gain time, argues Ian Hughes.

Practical work is a key part of degree courses in biological sciences. It teaches students how to plan experiments, handle equipment, manipulate biological materials and gather data. They learn about safety, accuracy and biological variation. Finally, they write up their results.

This write-up occupies considerable student time, and an instructor with large classes can spend many hours marking a metre-high pile of lab books. Is this time well spent? The following snippet of conversation I overhead between two students suggests it may not be:

"What d'you get?"
"70 per cent - and you?"
"45 per cent again."
"Bad luck - let's get a coffee."

What is missing is any recognition of the comments and feedback that I had spent several hours writing. For these students, it was the mark that was important, not the comments designed to help learning. This realisation - together with the fact that some students made the same mistakes in subsequent write-ups despite having had them corrected and despite having covered in practical classes their poor performance in answering end-of-course examination questions - made me think there must be a better way.

Assessment of student write-ups should be accurate, efficient, reproducible and related to the learning objectives. It should also monitor student progress, develop critical abilities, provide feedback and stimulate learning.

Sadly, although the grading and monitoring aspect of assessment is well recognised, the learning opportunity presented by assessment is not generally well utilised by students or fully exploited by staff.

One solution may be peer assessment, basically students marking other students' work. The benefits of peer assessment are that it:

  • Provides each student with a full explanation of what should have been done
  • Requires students to understand better the material they are dealing with
  • Develops students' critical evaluation skills
  • Improves learning
  • Allows students to see what others achieve
  • Prepares students for a work environment in which they must assess the work of others
  • Saves staff time and effort.

First-year laboratory practicals in many science disciplines involve students following a practical schedule, collecting data, processing and explaining it and writing it up to a specified format. The following describes how a peer-assessment exercise worked with our first-year pharmacology students.

After the advantages of peer marking were explained to the students, they were given a write-up at random. They also got a marking schedule, which I then went through to illustrate each point. Students annotated the write-up they were marking, totalled the marks and signed to accept responsibility for the marking accuracy.

Marks were recorded, and the marking schedule and write-up were returned to the student. To test the reproducibility of marking, three copies of the same write-up were peer marked independently by students as part of the normal marking session. The marks awarded differed by only 2 per cent, which demonstrated the consistency of the process. Data regarding marks awarded for write-ups from two student cohorts are shown in the graph. Write-ups were marked by academic staff (me) for the first cohort, and peer marking was used for the second.

The data show that the two cohorts obtained similar marks for the first write-up (indicating they were of similar ability), but the cohort using peer-marking then obtained consistently better marks for the write-ups of experiments that followed. The validity of peer marking was confirmed by the correspondence between the peer-awarded mark and the staff-awarded mark on a sample of write-ups marked as a control.

The students' reacton to peer marking was not overenthusiastic. Many made comments such as "Don't you get paid for this?" or complained that it was too much work and that they were "really bushed at the end of marking". Nevertheless, peer marking fulfils many of the criteria for good assessment and has several educational advantages. As a bonus, peer marking can also save large amounts of staff time (peers can mark more than 200 write-ups in an hour, the same task would take a tutor 12-15 hours).

Although several years of experience with peer assessment have made me an enthusiast, there are snags. Providing a marking schedule makes it possible for the schedule to be passed to next year's students. I now use three practicals in rotation to avoid this problem. Peer marking must take place quite soon after the practical class or students will have forgotten what they did. Peer marking works well in first and second year, where everyone gets the same data by following the same schedule. If students can choose several different ways to do the practical, the marking schedule becomes unworkably complex.

Having discovered my "better way", I have also used it well in final-year communications and on poster presentations. But it did not work well with long essays, possibly because of the lack of an explicit marking schedule.

Peer marking has advantages for students and academics. But its validity as an accurate and effective summative assessment depends on the situations in which it is used. I would be interested to hear from others who have used peer marking in other circumstances.

Ian Hughes is professor of pharmacology education and co-director of the subject centre for bioscience, University of Leeds. Email:


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