Measuring pre-service chemistry teachers’ graph and table interpretation skills: when performance meets confidence

Abstract This study investigates pre-service chemistry teachers’ ability to interpret data in graphs and tables, justify their responses, and reflect on their performance using a multi-tier diagnostic Graphs and Tables Engagement (GATE) test. A mixed-methods approach involved 55 pre-service teachers from four Czech universities at the start of their studies. The instrument comprised nine tasks across four tiers: content questions, explanation justifications, and associated confidence judgments using a 100 mm visual analogue scale. It showed strong psychometric properties, including high reliability (Cronbach’s alpha = 0.93), satisfactory discrimination indices, and appropriate item difficulty. Students demonstrated moderate data extraction skills (mean Content Score = 0.66) but struggled more with justifications (mean Explanation Score = 0.51), resulting in a Total Score of 0.48. Confidence judgments illuminated cognitive and metacognitive processes: students generally exhibited high confidence in simpler tasks involving direct data retrieval but displayed notable miscalibration in more complex inference-based tasks. Significant differences in confidence between successful and unsuccessful respondents underscored the value of confidence data in distinguishing understanding from guessing. The multi-tier test effectively assessed students’ data interpretation skills but revealed the need for additional qualitative methods – such as eye-tracking, think-aloud protocols, and interviews – to comprehensively understand students’ strategies and guide instructional improvements.