This paper focuses on the procedure and results for analyzing text-difficulty in lower-secondary chemistry textbooks in the Czech Republic. The authors use established methodology for text-difficulty analysis by Nestler, adapted by Průcha and Pluskal by adding a second independent analyser to improve reliability. Some textbooks do not follow the expected trend of either text-difficulty coherence or increasing text-difficulty between books for the 8th and 9th grade. No trend in topic difficulty was found either. The results show that learning outcomes may differ significantly when different books are used, despite the fact that they are supposed to support the same curriculum. For this reason, the results serve to support not only teachers when selecting a textbook, but also researchers as a starting point for lesson observations.

中文翻译：

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初中化学教科书的课文难点分析

本文重点介绍了捷克共和国低中学化学教科书中分析文本难度的程序和结果。作者使用由Nestler建立的文本难度分析方法，并由Průcha和Pluskal改编，方法是添加第二个独立的分析器以提高可靠性。一些教科书并没有遵循8年级和9年级之间书本上的文字难度连贯性或书本难度增加的趋势。也没有发现主题难度的趋势。结果表明，尽管使用了不同的书，尽管它们支持相同的课程，但学习结果可能会有很大的不同。因此，结果不仅为选择教科书的教师提供了支持，而且还为研究者提供了观察课堂的起点。