Abstract
Numerical or 'column' problems are widely used, especially in the lower grades of the first stage of primary school, as warm-ups, competitions, in order to consolidate numerical connections in pupils. However, they are also often used as a marking tool.
The aim of the workshop was to get the participants to think about what possible grading of a pupil's solutions to numerical problems tells teachers and pupils about his/her current knowledge and how to use such problems to diagnose pupils' difficulties. In this paper, we present a set of ten tasks that we used in a didactic test in mathematics within the project Understanding Teachers' Understanding of the Causes of School Failure and the Effectiveness of Educational Interventions.
Erroneous solutions to the tasks and reflections on the possible causes of the errors help us to reveal and describe the specific problems of Year 2 pupils. Attention is paid to suggestions for re-education steps for particular causes of errors.
We use a case study to show how some re-teaching procedures can be formulated for a particular pupil.