Examining the effects of laboratory instruction on high school chemistry students\u27 conceptual understanding of chemical equilibrium

At high school level, students are expected to predict the behavior of the chemical systems at equilibrium. Numerous research studies have evidenced that high school chemistry students presented difficulties with the topic of chemical equilibrium. Likewise, several studies have suggested that laboratory instruction may benefit students by providing concrete situations and practical experiences. Therefore, I investigated how the laboratory instruction about chemical equilibrium might help high school chemistry students to construct and apply meaningful mental models of macroscopic, molecular, and symbolic representational levels and understand this topic. In this study, high school student-constructed concept maps (n= 9) that emerged from pre- & post- laboratory instructional interviews about chemical equilibrium were scored against a teacher map using a rubric. I used these student-constructed concept maps in conjunction with the interviews as way to provide a 2D-representation of: (1) the students\u27 knowledge about chemical equilibrium and (2) the students\u27 use of the three representational levels. A scoring rubric was developed to: (1) holistic analyze the concept map configuration, (2) numeric analyze the accuracy of the links, and (3) classify the links on the map based on three representational levels. Inter-rater reliability for the scoring scheme was high (r= 0.82). Students-constructed concept maps and interviews proved to be helpful tools to assess students\u27 understanding of chemical equilibrium and students\u27 use of the three representational levels. The data analysis of the assessment instruments was performed using Dedoose ® (an online Web 2.0 software) were emerging trends from the analysis can be observed in a code cloud and bar graphs instantaneously. Results obtained using the quality of understanding scheme (used to score the interviews) and the link accuracy rubric (used to score the concept maps) revealed that after the instruction the students showed partial understanding of the relation between the concepts related to chemical equilibrium. The levels of representations that students utilized to describe their understanding of chemical equilibrium were also classified. After the instruction, the students favored symbolic and macroscopic/symbolic levels of representation to describe chemical equilibrium

Assessing the factors that affect the way(s) high school chemistry students write effective laboratory reports

In the past, many claims have been made about the value of laboratory work in high school chemistry courses. Educators have emphasized that laboratory work helps students engage in scientific reasoning, such as critically evaluating data, debating ideas, and supporting claims with evidence. However, research concerning laboratory instruction indicated that the fundamental focus of many students in the laboratory is on completing the task and not on how to interpret or present their results in an effective laboratory report. This study investigated how students\u27 perceptions and attitudes, integrated laboratory/classroom instruction, and the type of laboratory activities/experiments affected high school chemistry students\u27 ability to write effective laboratory reports. Ten high school students (4 students enrolled in Chemistry I and 6 students enrolled in Honors Chemistry) participated in this study. Data sources for this analysis included questionnaire, student interviews, classroom observations, and documents written by students. The questionnaire consisted of two sections: a Likert scale survey and free response questions. The survey was used to assess the qualities of the classroom learning environment from the students\u27 perspective. The free response section contained a series of questions that explored students\u27 perceptions and attitudes of the laboratory instruction. The individual semi-structured interviews were conducted to probe student ideas about how the act of writing effective laboratory reports may have impacted their understanding of chemistry and their ability to write. Classroom observations and written documents were used to gather data regarding the context in which participants conducted laboratory experiments and write laboratory reports. Analysis of the questionnaires and interviews identified four main factors that students perceived to be important for writing an effective laboratory report within the high school chemistry laboratory context: (a) format of the laboratory instruction influenced student writing of laboratory reports; (b) laboratory instruction, especially laboratory reports, contributed to their understanding and learning of the chemistry concepts; (c) laboratory instruction and class work should be integrated and related; and (d) laboratory instruction should provide students with the opportunity to conduct more experimentation on their own, where they can pursue their own chemistry interests. Further research is needed to investigate students\u27 perceptions about their own learning of science as they engage in writing laboratory reports

Implementation and Assessment of Student-Made Microfluidic Devices in the General Chemistry Laboratory

Microfluidic technologies exploit the distinctive physical phenomena present at the nano and microscale. From the refinement of classic laboratory techniques and the integration of multiple laboratory processes in a single device, to the development of the organ-on-a-chip concept, the field of microfluidics is changing the way in which scientists across disciplines conduct cutting-edge research. Facilitating access to microfluidic devices for new generations of science students at the high school and undergraduate level will be instrumental in creating awareness of the current and potential uses of this technology. The aims of this work are to present students with a hands-on introduction to the field of microfluidics and to make available the device\u27s unique properties for the teaching of basic chemistry concepts. The approach utilizes thermal lamination as a dynamic, low cost method to provide students with the ability to design, fabricate, and test high quality microfluidic devices in a single session of the general chemistry laboratory. Thermal lamination differs from other chip-building techniques previously used in the classroom in that device fabrication takes place in a matter of minutes and does not require soft-lithography, etching, nor the use of PDMS or glass. The student-made devices are robust, have well defined dimensions and may adopt a wide variety of channel designs. We implemented an experiment in which students tested pre-built devices as well as devices of their own design, and measured a positive impact on their perception of microfluidics and micro and nanoscale phenomena like laminar flow and diffusion. The student\u27s conceptual understanding of microfluidics was also improved after the experiment. A detailed description of the approach and a comprehensive assessment of the student experience are provided