József Varga, Krisztián Józsa AND Róbert PapSzigeti: The criterion referenced development of the skill of proportion calculation in grade 7 Research has clearly shown that the basic skills and abilities of Hungarian students are not at appropriate developmental levels. The less than proficient operation of these basic skills and abilities hinders knowledge acquisition. Helping the development of abilities with criterionreferenced methods may address these problems. This study presents the results of an experiment aiming for the criterionreferenced development of one of the basic skills, proportion calculation. The sample comprised of N=209 students in the experimental group and N=129 in the control group, all from grade 7. The intervention lasted for 8 weeks, during which the control groups followed the regular curriculum concerning proportion calculation, while the experimental group was also exposed to additional developmental tasks. Based on pretest results, students were assigned to three performance categories and the tasks were selected to suit their developmental levels. Special attention was paid to activating academic motives. Students in the control group showed an 8 percentage point average gain during the intervention period, while those in the experimental group gained 29 percentage points. The effect size of the experiment is 0.48. Theoretical considerations point to a performance of 90 percentage points as the criterion of the optimal acquisition of the skill of proportion calculation. At the time of the pretest, neither the experimental, nor the control group demonstrated this proficiency. On the posttest, onethird of the students from the experimental group and onetenth from the control group were found to have reached this optimal developmental level. In the control group, prior knowledge was determining later development to a greater extent than in the experimental group. As a result of the intervention, the system of subskills, the structure of the skill as a whole became more pronounced. MAGYAR PEDAGÓGIA 107. Number 1. 527. (2007) Levelezési cím / Address for correspondence: Varga József, Bányai Júlia Gimnázium, H–6000 Kecskemét, H–6000 Kecskemét Nyíri út 11.; Józsa Krisztián, Szegedi Tudományegyetem, Neveléstudományi Intézet, H–6722 Szeged, Petőfi S. sgt. 3034.; PapSzigeti Róbert, Kecskeméti Főiskola, GAMF Kar, Informatika Tanszék, H–6000 Kecskemét, Izsáki út 10. 
