Development and validation of a four‑tier test for the assessment of secondary school students’ conceptual understanding of amino acids, proteins, and enzymes

Abstract

Previous studies noted the scantiness of diagnostic instruments for the assessment of students’ understanding of fundamental biochemistry concepts. Consequently, within this study, a four-tier test for the examination of secondary school students’ conceptual understanding of amino acids, proteins and enzymes has been developed. Items in the test consist of the answer tier, the reason tier and a confidence rating for each of these tiers. Following the three-phase development process, the final version of the test, comprising eight items, was administered to 123 students in the main study. The internal consistency of both cognitive scores and confidence ratings proved to be adequate (Cronbach’s alpha values were 0.76 and 0.87, respectively) and the test-retest reliability was also satisfactory (Pearson’s r value was 0.74 for the cognitive scores and 0.88 for the confidence ratings). If the correct responses to both the answer and the reason tier of items are considered, the mean score on the test was 3 out of 8 (38%). The students were more confident when producing the correct compared to the wrong answers but, overall, their confidence was not high (3.65 out of 6). Furthermore, the confidence in the incorrect answers that were provided (3.52 out of 6) indicates the presence of alternative conceptions. Such results show that the content regarding amino acids, proteins and enzymes is conceptually challenging for the students. Therefore, the test can help secondary school teachers to uncover the students’ conceptual difficulties related to this content and develop effective strategies for their remediation and prevention.