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PISA 2015: An Interview with Prof. Dr. Köller

1. December 2017

Professor Köller, the latest PISA results were published at the end of last year. This time science achievement was a focal point. The results were satisfactory, as students in Germany scored above the OECD average. Some critics argued that Germany had not succeeded as the performance of students in mathematics and science was somewhat weaker than in previous PISA rounds. What do you think of the results?

Köller: First of all, it is true that students are significantly above the OECD average in all tested areas - reading, mathematics, science. At the same time, there was a decline in performance in mathematics and science compared to PISA 2012. However, for the first time tests were implemented using computers and not - as before PISA 2015 – using test booklets and pencils. Hence, it was unclear whether performance had actually dropped or the results were distorted by the change of test medium.

Are the results from PISA 2015 comparable to those of the previous studies when test conditions had changed?

Köller: We conducted secondary analyses to investigate this question. It was helpful that the OECD carried out a so-called mode effect study a year before the PISA main survey. The same tasks were given once on the computer and once in the standard test booklet form and student groups randomly assigned to both conditions were compared in terms of their performance. It turned out that for Germany the tasks in mathematics and science were more difficult on the computer than in the test booklet. We tried to correct the PISA-2015 results for this negative computer effect, and this indeed resulted in no decrease in achievement compared to 2012.

Why is it difficult for students in Germany to work on computer-based tasks?

Köller: Good question. There are indications from the supplementary surveys in PISA 2015 that computers are used less in German classrooms than in other countries. In PISA 2015, this may have led to the computer effect having a negative impact in Germany, but not in some other countries. It is fair to say, however, that many countries performed worse in PISA 2015 than in 2012.

It was apparent in the early PISA rounds that a large group of students in Germany show such poor performance that a successful school-to-work-transition seems doubtful. How is this group of weak students today?

Köller: The group has become smaller – whereas, in PISA 2000, more than 25% of 15-year-old high school students in the sciences belong to this group at risk, today it is well below 20%. However, it is up to the school system to further reduce this number.

If you look at the other end of the scale: Will schools in Germany manage to foster high achievers?

Köller: This problem may have been underestimated in the past. The performance gains we experienced between PISA 2000 and PISA 2015 are ultimately only due to improvement in the lower end of the range. Justifiably, the system has taken care of PISA 2000's underachievers and now more attention must be paid to the high achievers. The federal and state governments have also responded by launching a campaign to foster talent.

How would you summarize the more than 15 years that PISA has been around?

Köller: PISA has sparked many discussions in Germany about the quality of education. Today, the general public elects new state governments if they feel a false education policy is being pursued. Hence, the efforts to develop schools which benefit children are visible everywhere. If one trusts the findings, the system has improved significantly, especially in lower secondary school. This was confirmed by PISA 2015.

Thank you for the interview.