###### Abstract  
Given the increasing digitalization of education and the variety of available digital learning materials (dLMs) of differing quality, (pre-service) teachers must develop the ability to select appropriate dLMs. Objective, reliable, and valid assessment instruments are necessary to evaluate the effectiveness of that development. This study conceptualized and designed an economical four-item instrument for assessing \"selecting dLMs\" based on accepted frameworks and competence models. The scientific quality of the instrument was evaluated in Study 1 (\(n=164\)) with four dLMs and empirically investigated in a subsequent Study 2 (\(n=395\)) with pre-service mathematics teachers from two universities. The empirical results indicate that the instrument could objectively and reliably gauge different levels of \"selecting dLMs\". Furthermore, the results are consistent with the widely accepted notion that the competence of \"selecting dLMs\" depends on (content) knowledge; however, that relation was not strong. In addition, the results for objectively assessing \"selecting dLMs\" paralleled the results of self-assessed TPACK in terms of the academic progression of participants. The proposed approach allows for variations and integration of diverse dLMs, and it has the potential to be adapted in other subject areas and contexts. digital competence; pre-service teachers; student-teacher evaluation; technological advancement; decision-making skills; digital learning material +
Footnote †: journal: Applied sciences  
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tal technology and dLMs [7; 11]. However, for the instrument developed here, only the selection of dLMs, referred to as \"selecting dLMs\", is of relevance. In general, teachers play an essential role in successfully integrating dLMs into their lesson planning. They must be competent in \"selecting dLMs\" [1; 8; 12] to provide learners with appropriate learning opportunities [13]. This aspect of digital competence is also crucial for teachers as they are confronted with the rapid development of dLMs and the vast number of dLMs of varying quality [14; 15]. Developing this facet of digital competence during initial teacher training is therefore essential. Reliable and valid assessment instruments are needed to evaluate the effectiveness of that development [12]. The TPACK framework by [PERSON] and [PERSON] [16] describes that knowledge which pre-service teachers need to select digital resources, in general, and dLMs specifically. The framework is also widely used in assessments of pre-service teachers [11; 17; 18]. Two concerns arise regarding assessing the facet of \"selecting dLMs\" and the effort needed for its assessment. On the one hand, existing assessment instruments for teachers' digital competence require participants to, for example, evaluate the value of learning apps [14], the interpretation of video vignettes [19; 20], the use of static learning material [21; 22], or the evaluation of developed lesson plans incorporating digital resources [23; 24; 25], but none directly addresses the selection of dLMs. On the other hand, most instruments, especially those regarding the frequently used TPACK framework [11; 18; 26], are self-report assessments. They are criticized for lacking validity and subject specificity [27; 28; 29] and may suffer from social desirability bias [30; 31]. Because of the importance of \"selecting dLMs\" and the lack of open- and closed-text objective assessment instruments [11; 18], we propose assessing \"selecting dLMs\" using four closed and open-text items that require respondents to reason for or against selecting a given dLM for a specific learner's age, special learner's needs, and explicit learning content. The items and scoring proposed in this manuscript for assessing \"selecting dLMs\" were applied to diverse dLMs and hold the potential to be adapted to other teaching subjects.