[Differential learning effects in preventive drug education by peer group members]

In the drug prevention programme studied here, peers were acting as teachers for their colleagues. We focused on the contribution of student characteristics and of teaching quality to the gain in knowledge about drugs. 165 8th- and 9th-graders in eight classes answered a questionnaire three times: before, immediately after and five months after the intervention. There was a significant increase in knowledge immediately after the intervention (mean m = 6.2) and after five months (m = 6.1) compared to the score before (m = 4.5). Furthermore, non-German speaking students of the "Sekundarschule" (higher level) learned the most, non-German speaking students of the "Realschule" (lower level) learned nothing at all. We found a positive association between teaching quality as assessed by each class and knowledge gain in the same class. Multiple linear regression analysis showed that five months after the intervention student characteristics explained an important part of the variance in knowledge gain (25% of the total variance), while teaching quality explained another 5%. Consequently, these characteristics can serve as predictors of knowledge gain in such programmes.