Research On The Evaluation Of Middle School Students' Ability To Control Variable

The ability to control variables is not only one of the sub-dimensions of scientific reasoning ability,but also an indispensable key ability in scientific inquiry activities.the development of this ability is conducive to the formation and improvement of students’core literacy and has important practical significance.This study investigates the current situation of middle school students’ability to control variables,and discusses the development characteristics of middle school students’ability to control variables,so as to provide reference for further cultivating students’ability to control variables and improving their core literacy.First of all,Control of Variables Strategy Inventory(referred to as CVSI)developed by the Schwichou team is translated and revised.because there are too many CVSI projects,this study divides it into half and verifies its validity.The results show that the semi-test has similar mean,standard deviation,difficulty,discrimination and guessing parameters.The regression method shows that the semi-test score can be transformed into the original test score within a certain range of error.Then the measurement index of semi-CVSI is examined,and its internal consistency is examined by Cronbach’s alpha coefficient,the results show that the whole test and each sub-skill have reached a good level of reliability,and the Rasch model is used to check the quality of the test items,the results show that the overall quality of the test is good,but the fitting degree of individual items,such as 18 and 22,is not high.By using the revised test tool,taking junior and senior high school students as the research object,this paper evaluates their ability to control variables as a whole and the development level of their sub-skills,and probes into the influencing factors of the ability to control variables.in addition to the comparison and difference test in the aspects of school section,gender,school type and so on.The content knowledge evaluation tool is also used to examine the correlation between the mastery of content knowledge and the ability to control variables.In addition,the predictability of the control variable strategy test performance to the physics achievement was examined.The main conclusions are as follows:(1)the students’ability to control variables in middle school is at a high level as a whole.specifically,the three sub-skills of"planing controlled experiments"(PL),"identifying controlled experiments"(ID)and"interpreting controlled experiments"(IN)perform better,while the sub-skill of"understanding the indeterminacy of confounded experiments"(UN)still has room for improvement.Compared with junior high school students,senior high school students have reached a higher level in the overall ability to control variables and various sub-skills.The progress of the three sub-skills of PL,IN and ID is relatively obvious,and senior high school students can almost master these three sub-skills very well,but the progress of UN sub-skills is relatively small,and the students in junior and senior high school are relatively weak.(2)there was no significant gender difference in the total score of the test and the scores of the four sub-skills in junior and senior high school students.The average scores of secondary vocational school students on CVSI and sub-skills are slightly lower than those of ordinary senior high school students,but from a statistical point of view,there was no significant difference in total score,IN and ID sub-skill scores,PL sub-skill scores were significantly different,while UN sub-skill scores were very significant.The control variable ability of students in junior and senior high school shows a certain correlation with their content knowledge mastery,in which the correlation between UN sub-skills and content knowledge mastery is the lowest in junior middle school,but the highest in senior high school.(3)Compared with the six items about control variables in LCTSR 2000,there is a higher correlation between CVSI scores and physics scores.Through regression analysis,it is found that the coefficient R~2 of CVSI for physics scores is 0.332,indicating that CVSI is not effective in predicting physics scores.Based on the investigation and research,this paper puts forward some suggestions on the textbook revision,exercise compilation and teaching practice of the ability teaching of control variables.