Research suggests that difficulty in making connections
among three levels of chemical representationsmacroscopic,
submicroscopic, and symbolicis a primary reason for student
alternative conceptions of chemistry concepts, and computer modeling
is promising to help students make the connections. However, no computer
modeling-based assessment tools are currently available. This article
introduces an approach to using Rasch measurement to develop a computer
modeling-based instrument to assess students’ conceptual understanding
of matter. The instrument contained 15 multiple-choice and 3 constructed-response
questions. Two pilot tests were carried out in high schools both in
the United States and China. In pilot test I, the instrument was given
to 112 students. The partial-credit Rasch model was applied to the
data to examine item and test properties. The instrument was then
revised and given to 403 students in pilot test II. The partial-credit
Rasch model was applied again to the data, and noticeable improvements
were achieved in technical qualities of both items and the instrument
as a whole. This study demonstrates that using Rasch measurement to
develop computer modeling-based measurement instruments in chemistry
is promising.
Chemical symbol representation is used extensively in chemistry classrooms; however, due to its abstract nature, many students struggle with learning and effectively utilizing these symbolic representations, which can lead to ongoing failure in subsequent chemistry learning. Taking the perspective of learning progressions, this study identifies how students’ abilities in chemical symbol representation progress at different grade levels (Grade 10–12), across the genders. A sample of 713 students—254 tenth graders, 262 eleventh graders and 197 twelfth graders—was selected from three senior secondary schools located in Jiangsu, China. A measurement instrument developed in a former study was used to measure students’ chemical symbol representation abilities and students’ raw scores were converted into Rasch scale scores, allowing for direct comparisons of students of different grades. The results of chi-squared tests and analysis of variance (ANOVA) indicated that chemical symbol representation abilities are affected by statistically significant gender and grade effects. Students from higher grades performed better than students from lower grades, and generally, male students obtained a higher mean score than did their female peers. The findings also revealed that there was a statistically significant interaction effect between gender and grade. While male students started out with a much higher mean score in Grade 10, by Grade 11 there was not much of a difference between male and female students’ mean scores, and female students’ mean score was higher than male students’ mean score by Grade 12.
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