CHEM 101A - General College Chemistry - Stage 5 - Christina Stuart
Assessment
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| Assessment Description | Our assessments in Spring 2013 focused on our laboratory curriculum since we plan to make changes to this component of the course. Assessments included a pre- and post-survey covering student background, their perception of their skills, significant figures, laboratory technique, and one content question on titration. Some sample questions are listed below: 8. I feel my laboratory skills are: a. very strong b. strong c. average d. weak e. very weak 10. A beaker weighs 21.338 g. After adding some NaCl to the beaker, the mass is found to be 21.518 g. What is the mass of NaCl, to the correct number of significant figures? a. 0.2 g b. 0.18 g c. 0.180 g d. 0.1800 g e. 0.18000 g 14. If water is used to wash down the sides of a flask while titrating HCl with a known concentration of NaOH, the calculated concentration of HCl (in moles/liter) will: (circle one) a. be higher b. be lower c. unchanged In addition to collecting background information on our students (questions #1-8), the survey aims to gauge whether our lab curriculum adequately addresses three broad topics: laboratory technique, correct report of results, and chemical understanding. Laboratory technique (questions # 9, 11, 13) involves items such as choosing the correct glassware, reading markings on glassware to the correct decimal place, precise mass measurements. In this survey, correct report of results (questions #10, 12) is limited to significant figures. Chemical understanding (question #14) is evaluated using a single titration question. The success or failure of the lab curriculum to teach/reinforce each of these broad topics will be discussed individually. Mastery will assume that 65% of the students answered the question correctly. In addition to the survey results, we also collected data on student accuracy of determining an unknown in various experiments in the laboratory as an indirect report on student technique. The experiments evaluated topics such as thermochemistry, separation of mixtures, titration and absorption spectroscopy. Results of these activities are reported below. We also collected data from the final exam to evaluate whether students had mastered thermochemistry. |
| Learning Outcomes | B. Analyze and solve stoichiometry problems including limiting, elemental analyses, and material balances in aqueous solution. D. Derive energies and enthalpies of physical and chemical processes from calorimetric data, and solve problems involving enthalpies of formation and Hess’ law. E. Derive and use classical and modern relationships for electromagnetic radiation. L. Describe and use laboratory techniques, including proper recording of laboratory data, the proper use of weighing balances, spectrophotometers, and other equipment, the proper disposal of waste, and safety procedures and precautions. |
| Number of Sections | 6 sections for the pre and post survey, 4 sections for the report on student accuracy, 9 sections for exam question. |
| Number of Instructors | 5 instructors |
| Number of Students | ~160 students for the pre survey and ~110 for the post survey (differences are due to attrition throughout the semester). ~120 students for the report on student accuracy. ~140 students for the exam data. |
Data Analysis
| Data Shared With | Instructors of the same course (at CCSF) |
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| Data Summary | Data from the correct identifications of unknowns throughout the semester: -84% determined the composition of a mixture using separation techniques including filtration, distillation, and decantation. -83% determined the concentration of an acid using titration techniques. -53% determined the identity of their metal based on specific heat using calorimetry. -54% determined the concentration of a Cr3+ solution using absorption spectroscopy. Data from the pre- and post-survey given in lab: -92% of our students know how to read a buret before entering our course. (No change pre and post) -73% can report results to the correctly use significant figure rules. (No significant change pre and post) -40.6% don’t know how to most precisely and accurately deliver sample using a balance. -89.7% knew what type of glassware was appropriate for each task by the end of the semester (61.5% pre vs. 89.7% post). -79.4% knew what effect using water to wash down the sides of a titration flask would have on their end result (up from 37.7% pre), but only 56.6% understood the reasoning behind it (up from 34.0%). |
| Analysis Summary | With regard to laboratory technique, it seems that our lab curriculum succeeds in teaching some skills, but does not meet others. For example, students seemed to learn from our course how to select glassware for a given task, which was something that showed the most marked improvement between pre- and post-survey. However, some fundamental lab skills were not mastered by the end of the course. 40.6% of our students were unclear on how to most precisely measure out a sample on the balance at the end of the semester compared to 42.7% at the start. Unfortunately, this particular question may not be a good indicator of whether or not students possess this skill or not because the wording of the question was unclear. In the current iteration of the survey, the wording has been changed to hopefully gain some more meaningful data. Significant figures and how to read a buret were skills that students came in with mastered already. This is also reflected in 83% of the students correctly determining the unknown concentration of an acid, which relies heavily on their ability to correctly use a buret as well as stoichiometry calculations. This mastery of buret use is likely due to the fact that 66% of the incoming students had already taken Chem 40 (our prep course for Chem 101A) where basic lab technique is introduced. Although students are able to carry out titration experiments to yield accurate results, our survey shows that the theoretical understanding of the material is still not mastered. Students in our course were also able to employ basic separation techniques, while calorimetry and absorption spectroscopy mastery was not met. One possible reason for the lack of mastery in absorption spectroscopy may be this lab introduces a lot of new material to the students all at once. To help address this issue, we are implementing a new lab, which will introduce students to the use of a standard curve much earlier in the semester. We hope this change will allow students to better focus on the theory of absorption spectroscopy rather than grappling with the concept of a standard curve later in the semester. |
| Next Steps Planned | Although students already knew how to report their data to the correct number of significant figures before coming into our courses, we also want them to have a firm understanding of uncertainty in measurements and the impact this has on their reported value. To this end, we have introduced a new lab this semester to highlight the differences in glassware and the impact that it can have on their result. While we have always talked about error analysis, it has typically come later in the semester. This semester we introduced it in Experiment 1 so we can build on it the entire semester. We have added a question about error in our survey to measure student understanding. Since students seemed to struggle with absorption spectroscopy, we also made a couple of other changes to help students with this topic. The lab not only introduces the theory of absorption spectroscopy, but also introduces the idea of a standard curve. This is too much for the students to process in one lab. So what we have done is introduced the use of a standard curve in a new lab written this summer, so students are exposed to it before encountering more challenging topics. With the decoupling of the standard curve and theory of absorption spectroscopy, we hope to see their understanding improves. |
| Learning Outcomes | E. Derive and use classical and modern relationships for electromagnetic radiation. L. Describe and use laboratory techniques, including proper recording of laboratory data, the proper use of weighing balances, spectrophotometers, and other equipment, the proper disposal of waste, and safety procedures and precautions. |
Changes
| Details | 1. Two new experiments that highlight uncertainty in measurements and standard curves (implemented) 2. Revision to our absorption experiment to use fluorescene rather than Cr3+ (planned, but not yet implemented) |
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| Learning Outcomes | E. Derive and use classical and modern relationships for electromagnetic radiation. L. Describe and use laboratory techniques, including proper recording of laboratory data, the proper use of weighing balances, spectrophotometers, and other equipment, the proper disposal of waste, and safety procedures and precautions. |
GE Area C Details
| Learning Outcomes | D. Derive energies and enthalpies of physical and chemical processes from calorimetric data, and solve problems involving enthalpies of formation and Hess’ law. |
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| Number Students: Proficient | 70 |
| Number Students: Developing | 11 |
| Number Students: No Evidence | 53 |
| Criteria | We evaluated a question on our final exam using the following guidelines: “Proficiency” meant students scored 65% or more of the points available on that problem. “Developing” was set to be the 50-65% range; students understood pieces of the problem, but could not put everything together in a way that showed they knew the material. “No evidence” was for students who scored less than 50%. |
| Extra Details | No answer |
Tentative Future Plans
| Term | Fall 2013 |
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| More Details | We will continue to collect and review data related to accuracy and precision of lab techniques. Modifications of experimental procedures (and if necessary development of new experiments) will be considered for implementation in Spring 2014. |
SLO Details Storage Location
- HARD COPY - In my personal filing system (my office)
- ELECTRONIC COPY - In my electronic filing system (hard drive or web server)