In the last decades, many bilingual programs such as content and language integrated learning (CLIL) have emerged. A crucial question in CLIL is whether to assess students' content-subject knowledge in the common language or the dominant language of instruction. In two experimental field studies with N = 361 6th-graders and N = 703 8th-graders, we investigated test-language effects and their moderation by CLIL-experience, language background, instructional language use and item format. In both studies, students' achievement was higher when items were presented in the common language. This effect was less pronounced in experienced CLIL-learners and for multiple-choice than cloze-test items. Moderation effects of language background were only partially and for instructional language use not statistically significant. The results show that using the dominant language of instruction to assess content-subject knowledge in bilingual education might underestimate students’ learning and that test-language and item-format effects need to be considered.

在过去的几十年中，出现了许多双语课程，例如内容和语言集成学习 (CLIL)。CLIL 中的一个关键问题是是否评估学生在通用语言或主要教学语言中的内容学科知识。在N  = 361 六年级学生和N 的两项实验性实地研究中 = 703 名 8 年级学生，我们通过 CLIL 经验、语言背景、教学语言使用和项目格式调查了测试语言效果及其调节。在这两项研究中，当项目以共同语言呈现时，学生的成绩更高。这种效果在有经验的 CLIL 学习者和多项选择中不如完形填空测试项目明显。语言背景的调节作用只是部分的，对于教学语言的使用没有统计学意义。结果表明，在双语教育中使用主导教学语言评估内容学科知识可能会低估学生的学习，需要考虑测试语言和项目格式的影响。