The Integration of Submicroscopic Representations Used in Chemistry Textbook Sets into Curriculum Topics.

To support the understanding of chemistry concepts and processes at the particulate level, various representations are included in learning materials. This paper focuses on how submicroscopic representations (SMRs) are integrated into Slovenian chemistry textbook sets with respect to the curriculum topics for 8th and 9th Grade. Textbook set analysis is based on four holistic SMRs descriptors (direct, indirect, combined descriptor, and SMRs without descriptors), which support learners' recognition of SMRs' informational value at different levels by providing different accompanying SMRs add-ons. The textbook sets analysis revealed that the number of SMRs varies significantly with regard to different curriculum topics. The overall proportion of the descriptors that enable the learner a direct recognition of SMRs is low in all curriculum topics. Interestingly, the descriptors that do not enable the learners a direct recognition of SMRs prevail in textbook sets. To obtain more detailed insight into the criteria based on which the textbook authors integrate SMRs with various descriptors into textbook sets, further studies are necessary.

Beyond the use of an Explanatory Key Accompanying Submicroscopic Representations.

When learning chemistry, students encounter various visualizations introducing scientific concepts and processes unobservable to the naked eye. It is often assumed that these visualizations support students' understanding and enable them to solve problems more efficiently. The research presented here investigates students' use of an explanatory key while solving tasks based on submicroscopic representations. The following features of the explanatory key were examined: 1) colored versus black-and-white, and 2) pictorial versus textual. Eye-fixation patterns and students' verbal explanations indicated that the presence of color in the key does not influence students' task solving. However, significant differences were observed with regard to a textual versus pictorial key used in the tasks: students spent more time and fixated more frequently on the key while solving tasks using a textual key in comparison to a pictorial key. The results indicate that the type of explanatory key might play an important role in revealing students' representational competence with regard to submicroscopic representations.